Excellent video! Especially if you're trying to figure out if the sensor is bad, or if it's the wiring (as is the case with ANY code that has the word "circuit" in its description). I know it's kind of a nitpick, but if you're going to be using multiple test leads and extensions, do get in the habit of always using the red wires for positive, and black for the ground. Don't mix those colors and use other color leads elsewhere e.g. signal wires and such.
Very detailed. I followed your procedure very easily, and I really like all the tips that you told us. Thank you. I have a question though. I'm reading 12.7v to 12.8v in idle. Does this mean that my MAF is shot?
i know this is way too late to be useful, but maybe useful to someone else reading this. it's likely you were just reading the supply voltage, not the voltage between signal and ground.
Nice Video bud. i am a Mechanic too, and when i wash my work clothing i put some degreaser in the washing machine, and my clothes come out looking nice. just a tip.
Great question and it is not as complicated as it seems. The key thing is to remember that sometimes not all sensors are connected or, "referenced to ground". A or any computer can read a two-conductor/pin signal with no connection/reference to ground, meaning the computer has a sense-conductor going to the remote sensor and the a return wire leading directly back to the computer. In a six-wire configuration one can ASSUME (unknowingly until proven) that four of those wires are for the MAF and two are for the IAT sensor - the next person can also RIGHTLY assume that three of those wires are for the MAF and the other three are for the IAT sensor...this too is a correct postulation...one of the two assumptions can be correct...the other is wrong or even both can be wrong. At that point all that one can do is backprobe all six wires after doing their reseach of WHAT to expect and put the puzzle pices into the proper places...welcome to SCIENCE...it's never been just for the egg-headed dicks gettin' the A's in class in the Science lab, it's now great for you too!!! Just be careful and don't short those backprobe leads (use electrical tape for paperclip isolation) and you'll get there! Probe 'Em all as that famous Steer Wars character said back in '49 on the Saturday Night Live Special Friday-Saturday Night Marathon!!!! (Oh Wait...maybe that was '59...err) Cheeers MY Feller Greasy-Finger Print Dudes :-D Dan Gibbs :-D
Battery brand new. Starter brand new. Tested map, maf, fuel pressure, fuel volume, coil pack, o2, checked plugs, checked compression, oh yeah, new fuel and air filters. Checked battery cables and ALL grounds. Cranks like an air tool, still won't start.
@@anthonylawrence9307 I had a brand new starter too a few months ago but when parts stores test them they dont have a load on them. I got another starter and thats when mine worked. If you have a warranty on your starter why not try to get another one?
Today I'm going to waste my time, pull the starter, out drive 45 minutes, get yet another BRAND NEW starter, 45 minutes back, put it in, all for nothing. Back 40 years ago it "was always the carburetor", nowadays it can't be so it's the starter.
If the two connectors are connected, the wires that he narrowed down to be the signal + and - can be measured at either side of the connector! Polarity doesn't really matter in this instance, so there's no real need to figure out which signal wire was the - one. I'm sure you don't need this answer anymore, but here's to helping the next person who asks!
in MANY cars, unplugging the MAF while the engine is running and if motor doesn't die, it does NOT mean the MAF is OK!....the computer automatically goes to a default setting for MAF and other sensors pick up the 'fuel trim slack'also Ratchets guy here is testing an ANALOG MAF evidently and his voltmeter can test these, roughly.......also you should tap on the MAF housing while testing to see if you have an intermittent vibration issue failure.if you go thru his test and you get a 4.38 [+ - .05V] reading that goes down to approx. 3.8V as you rev the engine then you have a digital [frequency counting] MAF, but the reading does not absolutely indicate your MAF is OK......yes its working but still could possibly be giving out wrong values......but it IS somewhat of an indication.
Boat Man hey friend, I have a Nissan car with the QG16DE engine. While the engine was running, I unplugged the MAF sensor wire harness and the engine did NOT stop running, although it seemed to run erratically. I turned of engine, connected the wire harness to the MAF sensor, then everything was back to the way it was. Is there a problem?
Hello, forgive me didn’t catch your name. Never the less I felt compelled to 1st thank you for new insight I gained by watching this MSG video. Further more pay you a big thumbs up on how detailed but yet, listener friendly enough to be able to follow and understand what you said. Thanks buďdy
ok, I get it, I had to watch a couple times, this is a good way for a DIYer without a scope. I was trying to figure out how to connect a scope, which I don't think the shop did. I've got a phantom p0171 that won't go away, I tried a new MAF sensor but it returned, so I reverted to my old MAF sensor. I probably didn't let it run enough? - update: replaced MAF with proper OEM part and it worked fine.
@@Fireneedsair My problem was 171, my 'new MAF that I mentioned was from Amazon and non-oem, so later I learned of risk of counterfeit, or more likely just non-compliance. I now only get Denso for my Toyota and it fixed it. You can also clean them with MAF cleaner which may work (do not use brake cleaner or other, only MAF specific cleaner). I do not know P0170, it looks fuel related or something.
@@Fireneedsair Ugh, so you're on the right path, eventually all will be new - what kind of car? You replace both O2 sensors? Downstream doesn't control much, but it sounds like a Fuel Trim issues, to look at MAF and upstream O2 (Air/Fuel, which was my ultimate repair), then vacuum leaks (the real hidden gremlin, supposedly often a leak at exhaust manifold to exhaust pipe (up from cat). also check inlet air to air box, clamps on airbox, screws/seals to MAF, clamps to throttle body, any place air (unmetered) can get in can screw it up. You want to fix it soon because poor A/F ratio will cause compensation, which can poison the cat. Here's 20 minutes of some guy looking at such steps: ua-cam.com/video/tnA1vi6-U5M/v-deo.html
@@condomanager5259 got a 2001 Mitsubishi montero limited.got a pO170 which is a generic fuel trim code that tells me little. Replaced all 4 o2s but now one is getting no voltage so have to buy another one. Fixed a vacuum leak. The MAF appears to be working. I have NONE of the symptoms of fuel trim issues. The car idles perfect, no lag at all on acceleration. My STFT are way too high suggesting a lean mix. And….. the code can be triggered by other issues that have nothing to do with it. Damn emissions.got 3 weeks to figure this out or park the car. My mechanic tells me to also replace the MAF but they are pricey and I’m tired of throwing $$ away. Used a 5000$ scanner and no shop will tell me anything besides possibilities.ugh
First of all,my 93 maxima has a symptom, that when I accelerate,it hesitated to go. So, I performed the diagnostic procedures as you have shown. However, the last step was,to probe two paper clips to the back of the two wires,not the power and ground wires, but the other two wires,then started the car,but When I connected the multimeter,there was no voltage showed. Does that mean the mass sensor is gone or I did something wrong? Thanks
Great test. However I thought the MAF voltage varies according to the amount of air entering the engine and not to RPM. which means a better test would be to use a blower fan or compressed air and see if it reacts...I could be wrong but just curious...
This has nothing to do with checking MAF working condition. The way MAF works: basically MAF has a filament( tiny wire) which gets hotter as engine RPM increase. I 1) ECU sends a voltage through MAF’s filament. 2) MAF is located inside air intake 3) When RPM increase, ECU send more current and filament gets hotter, wire resistance increases with temperature 5) ... but with increased RPM, there more air flow and that cools the filament down, decreasing resistance. 6) the other two wires, connected to MAF sensor, read a resistance values and send them to ECU. (Four wires total- 2 to heat up the filament, other 2-to read the resistance and send it to ECU 7) ECU is programed to read specific values with specific RPMS. So RPM go up, ECU send more current to MAF, MAF cools down by more flowing air, ECU gets info and analyzes it, if MAF is bad, readings dont match to default, ECU panics and lights up a CHECK ENGINE! All you checked here is the voltage that ECU sends to MAF. You never checked the readings of the other two wires. You didnt even show a MAF in this video.
I know this is late but If I'm having a reading of MAF intake in g/s with my scanner, then that means my maf sensor is still working right? Trying to diagnose with my chevy captiva. The maf sensor reading is 15g/s with my old one and now that I have a new one, it's also 15g/s. Color me confused
Great video.My Subaru has no 5V reference voltage. Only 12, signal and ground. It's hard to understand that your car has two power sources 12 and 5V. Do they connect to the hot wire inside the sensor directly? Imagine. what would happen if we feed a bulb with two different batteries( one is 12V, another is 9V)?
To diag a MAF all you need to do is monitor the MAF data stream on a scam tool. An engine will draw in a certain amount of air per engine size. To diag look at the data stream for the MAF sensor with the engine at idle. Data is read in grams per second. A 3.0 liter engine MAF sensor should report at least 3.0 grams per second at idle. If the reading is higher than 3.0 grams per second your MAF sensor is fine. If it's below the spec inspect your engines Intake system for leaks. Look at the air filter condition. Inspect for exhaust leaks ahead of the first O2 sensor. If all is well no leaks and the sensor still reads below 1 gram per second for each liter of engine size, remove the sensor and inspect for dirt or contamination on the hot wire in the sensor. Clean it with MAF sensor spray cleaner and retest. If the readings are still below normal recheck your previous work for vacuum and exhaust leaks and if all is well replaced the sensor I have fixed many many other techs comebacks after they replaced a MAF sensor but didn't verify engine integrity. Usually it's a vacuum leaks in the intake stream or an exhaust leak at the manifold doughnut gaskets. Retired after 40 years as a GM tech. It amazes me how many people don't bother to read or understand the proper diagnosis in auto repair.
Hello sir Im a long time subscriber, i just want to ask if the signal wire in the maf sensor have voltage of .75v when disconnected, suppose to be 0v what is the pissible problem?
Love your videos and that is a great test if you can get the car to run. I suspect mine may be out because it is backfiring through the intake and I also have starter kickback when cranking
is the reason we don't want to let the test leads cross simply because it could give us a misleading response from the MM? or will it damage my car or MM? thanks!
A 2002 Lincoln Towncar...no related codes...I noticed the MAF sensor aint the original...is it possible this can cause issues without throwing out codes. Im gonna perform these tests next
I was trying to test my mass air flow sensor on my ‘99 tacoma and when I inserted the needle in one of the wires the truck went off and now it doesn’t start, it just tries but doesn’t go on, can you please guide me on what to look at to make it go on? The sensor on my Tacoma has six pins
Is it a coincidence? The MAF g/s at idle is close to my engines displacement size in liters and when I rev it, the g/s climbs up proportionally to rpm.
HI BROTHER, I GET LITTLE CONFUSED ON THIS VIDEO. I AM NO MACHANIC BUT I SPENT LOT OF MY TIME LOOKING AT MACHANICS`S VIDEOS. HERE IS MY CONFUSION. 1. YOU GOT 12 V ON SUPPLY WIRE, BUT WHEN I WATCH OTHER PEOPLE`S VIDEOS THEY SAY THERE MUST BE 5V SUPPLY. WHAT IS TRUE. 2. SOME PEOPLE SAY WHEN YOU CHECK FOR CONTINUITY THE CIRCUIT MUST BE OFF, BUT YOU DID NOT UNPLUG THE BATTERY WHEN CHECKING GROUND. M.B.S MOSHITOA (S AFRICA)
During the testing of the MAF sensor, the multimeter setting you used was DC voltage to monitor fluctuation. Would it not better(more accurate) to use the hertz setting on your multimeter to monitor fluctuation to see if your MAF sensor is good or bad? Thanks
Great engineer, please help me out. Recently, a client called me to fix his 2000 Toyota Avalon car that cranked but wasn't starting. From the onset, the car experienced several mechanical, as well as, electrical issues. Some of those problems were:- (1) Engine Oil consumption; (2) Engine misfire; (3) Engine rattling; (4) Intermittent hard starting after shutdown; (5) Hard to engage in drive, except engine is hot; etc. Hence, he took the car to a garage inorder to rectify the excessive Engine oil consumption and other car problems highlighted above. Consequently, the car problems exacerbated after engine rebuild by the engineer! The car owner wasn't satisfied with his repairs because it seems the engineer was deceitful. Although the car started after the rebuild, the problems still persisted. Valves weren't grinded after engine overhaul, engine still misfired at idle and when accelerating, etc. The engineer whose garage the car is presently being parked, requested for another engine overhau/ rebuildl. After engine rebuild the car started, the oil was mixed with water; the engine was still misfiring, rattling, etc. It was obvious, that he didn't use durable parts to do his work. Hence, the car owner moved the car to another garage for better repairs. The new garage suggested to the car owner that another engine rebuild is pertinent for optimal engine operation. During my conversation with this engineer, whose garage the car is presently being parked, he told me that: "when the car was first brought in, he noticed a black smoke ( maybe he was mistaken for blue smoke, at exhaust tail at idle). When accelerating, there's a loss of power, engine bucking, popping,etc. After the rebuild, the car didn't start because the mechanic didn't unlock the car with the remote but proceeded directly to cranking the engine. In addition, the security relay wasn't actuated for starting to take place. Electrician did some wire cutting around that axis which he said was corrected to factory, opened with a remote before the car started. Fortunately, after everything, the car started again. But there was still an intermittent misfire. What the car owner said was that, 'even when the second mechanic did engine rebuild, the car still misfired. Until he personally bypassed earth from the COP wire to the solenoids very close to the fuel injector often tightened with 10mm knot and depicted with blue and green colors on the picture. Car owner verified that the reasons for the misfire from both mechanics which still prevailed, was due to the solenoid valve that wasn't opening. That's why when accelerating it experienced a loss of power, similar to that experienced by a faulty fuel pump. After gear oil replacement and test driven by the second mechanic , smoke started emanating from the engine bay. Precisely, from the fan relay that the car owner connected by himself. Within few minutes, the car shutdown by itself as if fuel is finished. As he tried to restart it, the car refused to. Infact, when the ignition switch was turned to Acc/ ignition position, battery and fuel light was not displaying in the dashboard/ instrument cluster. However, during cranking battery light glew faintly and start. But when throttled, it would shutdown. Electrician verified and replaced the alternator diode with a new one. When Ignition switch was turned to Acc/ ignition position, the battery and other lights came out brightly but when cranked to start engine wouldn't start again. Sadly, it still wouldn't start. I tried to scan for DTC codes, but my scanner wasn't communicating. I checked all fuses, power and ground at obd port, those checked ok. but my scanner isn't compatible to read CAN network. there are only 4 wires intact for the obd2 port. Furthermore, I added fuel through the intake to the engine, no change at all. I checked for spark and injector pulse. These things weren't present. But there was power to injector with just the key at ignition or ACC and COP had 1 ground and 1 power as usual. Electrician from that garage, who also worked on the car said that he sniffed burning smell from the ECU, however personally I didn't when I went to start the car. I don't know how certain that was. Hence, I pulled out the ECU to a laptop board engineer to test the components inside. He said: "everything looks ok and test fine, however the IC he doesn't have the right tools to proceed with the test. With the ECU removed battery connected, Engine light would come ON. with ECU connected check light still comes ON. Before I left, I checked the MAF sensor 5 wires and noticed that 3 wires were earth instead of 2 and 1 power; no ignition current/ power was available for the remaining 2 wires. Please, what should I do to start the car?
how can I find out what the output voltage is supposed to be? Its at 0.65v without me blowing air into it. I Can get it to 1.5v if I blow at it.. I don't know what readings it's supposed to have
I know this is years later but can we also look at g/s on a code reader to see if MAF is bad? I was told my MAF on my 6 cylinder should read between 5.0-6.0 g/s. It’s reading around .5 g/s. Any help out there?
I did this test and when i back probe MAF I get matching voltage as battery around 12.2 when car in on positions. When I start engine I get 13.3 to 13.7 volts. Then when i rev it goes up
how come you didn't rev it higher? I revved mine until I hit where my engine was stumbling and the volts jumped from 1.8 to 4.0 and everywhere in between erratically.
But this engine doesn't want to stay running. I'm checking all the wire connections. So far everything tests okay, as far as I can tell. I tried running it without the MAF connected. It wouldn't even start. Right now, it starts, then dies, like it's missing really bad.
You do a good job explaining exactly, but you don't show how the leads are connected throughout the entire video. Please show the whole set up otherwise beginners like myself can't do it. Thanks.
Hi dear have u ever had any maf signal wire showed 4.3 volt at idle then goes down smoothly like 4.2 .4.1 at higher rpm I can't figure it out power and ground is okay its 94 camaro z28 I drives better without maf thnx
The engine check light came up on my car, had it checked with obd sensor and code indicated P0101. Had MAF sensor replaced and light appeared still. What to do after this? You could tell every one to check for leaks, cracked intake boot, vacuum leaks, clogged or improperly installed air filter, and many more that cannot be mentioned here. Its alot of diagnosing for this horrible CEL code. Take it easy .
DangerDaveFreestyle b&c ? I thought it was a&b ? I’ll go back and watch again. If I’m wrong then that might explain why I was only getting like 3.8 volts and it never changed in voltage. He only shows you one that is good , what if like mine it only showed and stayed at 3.8 volts? If I did it right could this also indicate that it’s bad by doing this?
Ok, I did it wrong I believe. Went back to watch it again and he talks about identifying the constant voltage wire in the ground and then he says we need to test the remaining two wires which in his, it’s the two Signal wires. Now that makes sense to me. I guess I’ll be checking it again tomorrow.
I believe he probed the signal wired coming from the sensor. He determined which 2 wires are the suply power/and ground, and those values shouldn't change if everything is working properly. So you just need to measure the power out put from the sensor to the ecu. I hope this helped.
If you have a 6 pin connector and six wires going to the plug also your MAF sensor has a air temperature sensor combined in the MAF. Some models have the sensor mounted on the air box with two wires going to it where the air filter is located to monitor air temp as air temp will also play a role in how your computer adjust for fuel mixture also.
all you need to do to test M.A.S , first start the car, let it idle , and unplug the MAS wires connected to the sensor, if the car stop your sensor is good , if the car keeps running your sensor is bad. it takes 3 second ... No need for this elo tester
I really like the way you explain things. no chit chat just to the point. def thumbs up
Excellent video! Especially if you're trying to figure out if the sensor is bad, or if it's the wiring (as is the case with ANY code that has the word "circuit" in its description).
I know it's kind of a nitpick, but if you're going to be using multiple test leads and extensions, do get in the habit of always using the red wires for positive, and black for the ground. Don't mix those colors and use other color leads elsewhere e.g. signal wires and such.
The only time swapping multimeter leads matters is analog volt meters. What are you talking about?
Thank you very much for the sensor series! I'll be trying this one out for sure!
np, thanks for watching.
Very detailed. I followed your procedure very easily, and I really like all the tips that you told us. Thank you.
I have a question though. I'm reading 12.7v to 12.8v in idle. Does this mean that my MAF is shot?
i know this is way too late to be useful, but maybe useful to someone else reading this. it's likely you were just reading the supply voltage, not the voltage between signal and ground.
Nice Video bud.
i am a Mechanic too, and when i wash my work clothing i put some degreaser in the washing machine, and my clothes come out looking nice. just a tip.
10 BUCKS well spent, Thanks for an awesome video 🙂👍keep on producing these video's please , BLESS 😇
I have that exact same meter, mine was $50 at HF. I got mine back in 2017 or 2018. It still works great too.
Thank you. This made MAF diagnostics easy.
Would using an OBD2 reader to read how much air it's pulling be a good way of doing the same test or is checking the voltage a better test?
Do both
Really nice video! You are good at explaining what to do.
Fairly easy for a 4 pin MAF set up what about a 6 pin where you also have to isolate the IAT sensor wires?
Great question and it is not as complicated as it seems. The key thing is to remember that sometimes not all sensors are connected or, "referenced to ground". A or any computer can read a two-conductor/pin signal with no connection/reference to ground, meaning the computer has a sense-conductor going to the remote sensor and the a return wire leading directly back to the computer. In a six-wire configuration one can ASSUME (unknowingly until proven) that four of those wires are for the MAF and two are for the IAT sensor - the next person can also RIGHTLY assume that three of those wires are for the MAF and the other three are for the IAT sensor...this too is a correct postulation...one of the two assumptions can be correct...the other is wrong or even both can be wrong. At that point all that one can do is backprobe all six wires after doing their reseach of WHAT to expect and put the puzzle pices into the proper places...welcome to SCIENCE...it's never been just for the egg-headed dicks gettin' the A's in class in the Science lab, it's now great for you too!!! Just be careful and don't short those backprobe leads (use electrical tape for paperclip isolation) and you'll get there! Probe 'Em all as that famous Steer Wars character said back in '49 on the Saturday Night Live Special Friday-Saturday Night Marathon!!!! (Oh Wait...maybe that was '59...err) Cheeers MY Feller Greasy-Finger Print Dudes :-D Dan Gibbs :-D
What I love is how these vehicles that get tested in any video are always able to run. WTF DO YOU DO WHEN IT WON'T EVEN START
Uhh you test the battery and the starter duh.
Battery should have around 12.4 v and if your batterys good then its probably a bad starter
Battery brand new. Starter brand new. Tested map, maf, fuel pressure, fuel volume, coil pack, o2, checked plugs, checked compression, oh yeah, new fuel and air filters. Checked battery cables and ALL grounds. Cranks like an air tool, still won't start.
@@anthonylawrence9307 I had a brand new starter too a few months ago but when parts stores test them they dont have a load on them. I got another starter and thats when mine worked. If you have a warranty on your starter why not try to get another one?
Today I'm going to waste my time, pull the starter, out drive 45 minutes, get yet another BRAND NEW starter, 45 minutes back, put it in, all for nothing. Back 40 years ago it "was always the carburetor", nowadays it can't be so it's the starter.
Which ground did you use to measure the signal leads? The one of the harness or a battery/chassis? Or does it not matter?
If the two connectors are connected, the wires that he narrowed down to be the signal + and - can be measured at either side of the connector! Polarity doesn't really matter in this instance, so there's no real need to figure out which signal wire was the - one. I'm sure you don't need this answer anymore, but here's to helping the next person who asks!
in MANY cars, unplugging the MAF while the engine is running and if motor doesn't die, it does NOT mean the MAF is OK!....the computer automatically goes to a default setting for MAF and other sensors pick up the 'fuel trim slack'also Ratchets guy here is testing an ANALOG MAF evidently and his voltmeter can test these, roughly.......also you should tap on the MAF housing while testing to see if you have an intermittent vibration issue failure.if you go thru his test and you get a 4.38 [+ - .05V] reading that goes down to approx. 3.8V as you rev the engine then you have a digital [frequency counting] MAF, but the reading does not absolutely indicate your MAF is OK......yes its working but still could possibly be giving out wrong values......but it IS somewhat of an indication.
Boat Man hey friend, I have a Nissan car with the QG16DE engine. While the engine was running, I unplugged the MAF sensor wire harness and the engine did NOT stop running, although it seemed to run erratically. I turned of engine, connected the wire harness to the MAF sensor, then everything was back to the way it was. Is there a problem?
Great explanation!
Hello, forgive me didn’t catch your name. Never the less I felt compelled to 1st thank you for new insight I gained by watching this MSG video. Further more pay you a big thumbs up on how detailed but yet, listener friendly enough to be able to follow and understand what you said. Thanks buďdy
Great video 👌 simply explained and straight to the point 🛠️🛠️🛠️🛠️🛠️👍
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😅😅
Well explained. Thank you.
ok, I get it, I had to watch a couple times, this is a good way for a DIYer without a scope. I was trying to figure out how to connect a scope, which I don't think the shop did. I've got a phantom p0171 that won't go away, I tried a new MAF sensor but it returned, so I reverted to my old MAF sensor. I probably didn't let it run enough? - update: replaced MAF with proper OEM part and it worked fine.
Ever find the problem? I have a p0170
@@Fireneedsair My problem was 171, my 'new MAF that I mentioned was from Amazon and non-oem, so later I learned of risk of counterfeit, or more likely just non-compliance. I now only get Denso for my Toyota and it fixed it. You can also clean them with MAF cleaner which may work (do not use brake cleaner or other, only MAF specific cleaner). I do not know P0170, it looks fuel related or something.
@@condomanager5259 I cleaned it. I’m going crazy trying to get the car to pass emissions. Replaced o2 sensors,fixed a vacuum leak. It’s so frustrating
@@Fireneedsair Ugh, so you're on the right path, eventually all will be new - what kind of car? You replace both O2 sensors? Downstream doesn't control much, but it sounds like a Fuel Trim issues, to look at MAF and upstream O2 (Air/Fuel, which was my ultimate repair), then vacuum leaks (the real hidden gremlin, supposedly often a leak at exhaust manifold to exhaust pipe (up from cat). also check inlet air to air box, clamps on airbox, screws/seals to MAF, clamps to throttle body, any place air (unmetered) can get in can screw it up. You want to fix it soon because poor A/F ratio will cause compensation, which can poison the cat. Here's 20 minutes of some guy looking at such steps: ua-cam.com/video/tnA1vi6-U5M/v-deo.html
@@condomanager5259 got a 2001 Mitsubishi montero limited.got a pO170 which is a generic fuel trim code that tells me little. Replaced all 4 o2s but now one is getting no voltage so have to buy another one. Fixed a vacuum leak. The MAF appears to be working. I have NONE of the symptoms of fuel trim issues. The car idles perfect, no lag at all on acceleration. My STFT are way too high suggesting a lean mix. And….. the code can be triggered by other issues that have nothing to do with it. Damn emissions.got 3 weeks to figure this out or park the car. My mechanic tells me to also replace the MAF but they are pricey and I’m tired of throwing $$ away. Used a 5000$ scanner and no shop will tell me anything besides possibilities.ugh
Still relevant! Thank you.
First of all,my 93 maxima has a symptom, that when I accelerate,it hesitated to go. So, I performed the diagnostic procedures as you have shown. However, the last step was,to probe two paper clips to the back of the two wires,not the power and ground wires, but the other two wires,then started the car,but When I connected the multimeter,there was no voltage showed. Does that mean the mass sensor is gone or I did something wrong? Thanks
Thank u. This was allot more detailed than the other video.
Good job explaining things. Thank you.
Nice video. Right to the point.
Great test. However I thought the MAF voltage varies according to the amount of air entering the engine and not to RPM. which means a better test would be to use a blower fan or compressed air and see if it reacts...I could be wrong but just curious...
+Younex Meures more rpm means more airflow will be present in the maf sensor so same thing
Excellent video! Very well explained and demonstrated. Thank you so much for your time and effort in producing this video.
Brillant video
Excellent video. Just a question, is Arnie you brother?
This has nothing to do with checking MAF working condition.
The way MAF works: basically MAF has a filament( tiny wire) which gets hotter as engine RPM increase. I
1) ECU sends a voltage through MAF’s filament.
2) MAF is located inside air intake
3) When RPM increase, ECU send more current and filament gets hotter, wire resistance increases with temperature
5) ... but with increased RPM, there more air flow and that cools the filament down, decreasing resistance.
6) the other two wires, connected to MAF sensor, read a resistance values and send them to ECU. (Four wires total- 2 to heat up the filament, other
2-to read the resistance and send it to ECU
7) ECU is programed to read specific values with specific RPMS. So RPM go up, ECU send more current to MAF, MAF cools down by more flowing air, ECU gets info and analyzes it, if MAF is bad, readings dont match to default, ECU panics and lights up a CHECK ENGINE!
All you checked here is the voltage that ECU sends to MAF. You never checked the readings of the other two wires. You didnt even show a MAF in this video.
Total bulshit
I know this is late but
If I'm having a reading of MAF intake in g/s with my scanner, then that means my maf sensor is still working right?
Trying to diagnose with my chevy captiva. The maf sensor reading is 15g/s with my old one and now that I have a new one, it's also 15g/s.
Color me confused
You’ve explained how the MAF works better than any video I’ve seen. Thank you very, very much.
Very helpful and direct to the point. Gracias
Gera Garcia np, thanks for watching.
Great video.My Subaru has no 5V reference voltage. Only 12, signal and ground. It's hard to understand that your car has two power sources 12 and 5V. Do they connect to the hot wire inside the sensor directly? Imagine. what would happen if we feed a bulb with two different batteries( one is 12V, another is 9V)?
Great video, thank you!
Good job man.
To diag a MAF all you need to do is monitor the MAF data stream on a scam tool. An engine will draw in a certain amount of air per engine size. To diag look at the data stream for the MAF sensor with the engine at idle. Data is read in grams per second. A 3.0 liter engine MAF sensor should report at least 3.0 grams per second at idle. If the reading is higher than 3.0 grams per second your MAF sensor is fine. If it's below the spec inspect your engines Intake system for leaks. Look at the air filter condition. Inspect for exhaust leaks ahead of the first O2 sensor. If all is well no leaks and the sensor still reads below 1 gram per second for each liter of engine size, remove the sensor and inspect for dirt or contamination on the hot wire in the sensor. Clean it with MAF sensor spray cleaner and retest. If the readings are still below normal recheck your previous work for vacuum and exhaust leaks and if all is well replaced the sensor
I have fixed many many other techs comebacks after they replaced a MAF sensor but didn't verify engine integrity. Usually it's a vacuum leaks in the intake stream or an exhaust leak at the manifold doughnut gaskets.
Retired after 40 years as a GM tech. It amazes me how many people don't bother to read or understand the proper diagnosis in auto repair.
Can I get ohms reading from the MAF sensor with out it being connected?
Hello sir Im a long time subscriber, i just want to ask if the signal wire in the maf sensor have voltage of .75v when disconnected, suppose to be 0v what is the pissible problem?
Good vid, nice and clear. i learned something today ;)
grate video.thanks
Love your videos and that is a great test if you can get the car to run. I suspect mine may be out because it is backfiring through the intake and I also have starter kickback when cranking
Are you sure it’s not timing related?
is the reason we don't want to let the test leads cross simply because it could give us a misleading response from the MM? or will it damage my car or MM?
thanks!
Important question. I wish he had clarified that.
Is there any way to test the MAF sensor completely off the car at all? Just asking..
A 2002 Lincoln Towncar...no related codes...I noticed the MAF sensor aint the original...is it possible this can cause issues without throwing out codes. Im gonna perform these tests next
Thanks
very nice videos
I was trying to test my mass air flow sensor on my ‘99 tacoma and when I inserted the needle in one of the wires the truck went off and now it doesn’t start, it just tries but doesn’t go on, can you please guide me on what to look at to make it go on? The sensor on my Tacoma has six pins
Is it a coincidence? The MAF g/s at idle is close to my engines displacement size in liters and when I rev it, the g/s climbs up proportionally to rpm.
nice one👍
HI BROTHER, I GET LITTLE CONFUSED ON THIS VIDEO. I AM NO MACHANIC BUT I SPENT LOT OF MY TIME LOOKING AT MACHANICS`S VIDEOS.
HERE IS MY CONFUSION.
1. YOU GOT 12 V ON SUPPLY WIRE, BUT WHEN I WATCH OTHER PEOPLE`S VIDEOS THEY SAY THERE MUST BE 5V SUPPLY. WHAT IS TRUE.
2. SOME PEOPLE SAY WHEN YOU CHECK FOR CONTINUITY THE CIRCUIT MUST BE OFF, BUT YOU DID NOT UNPLUG THE BATTERY WHEN CHECKING GROUND.
M.B.S MOSHITOA (S AFRICA)
and when realising that the sensor is damaged ... what to do than ??
caus i had no signs , that cables are damaged ,,, than what to do ?? thanks
Very nice
in which pin did you put your paper clip? I didn't get that part clearly.
pin 1 = signal (analogue voltage), pin 2 = ground (-)
During the testing of the MAF sensor, the multimeter setting you used was DC voltage to monitor fluctuation. Would it not better(more accurate) to use the hertz setting on your multimeter to monitor fluctuation to see if your MAF sensor is good or bad? Thanks
Thanks Bro
Great engineer, please help me out.
Recently, a client called me to fix his 2000 Toyota Avalon car that cranked but wasn't starting.
From the onset, the car experienced several mechanical, as well as, electrical issues. Some of those problems were:-
(1) Engine Oil consumption;
(2) Engine misfire;
(3) Engine rattling;
(4) Intermittent hard starting after shutdown;
(5) Hard to engage in drive, except engine is hot; etc.
Hence, he took the car to a garage inorder to rectify the excessive Engine oil consumption and other car problems highlighted above. Consequently, the car problems exacerbated after engine rebuild by the engineer!
The car owner wasn't satisfied with his repairs because it seems the engineer was deceitful. Although the car started after the rebuild, the problems still persisted. Valves weren't grinded after engine overhaul, engine still misfired at idle and when accelerating, etc.
The engineer whose garage the car is presently being parked, requested for another engine overhau/ rebuildl. After engine rebuild the car started, the oil was mixed with water; the engine was still misfiring, rattling, etc. It was obvious, that he didn't use durable parts to do his work.
Hence, the car owner moved the car to another garage for better repairs. The new garage suggested to the car owner that another engine rebuild is pertinent for optimal engine operation.
During my conversation with this engineer, whose garage the car is presently being parked, he told me that: "when the car was first brought in, he noticed a black smoke ( maybe he was mistaken for blue smoke, at exhaust tail at idle). When accelerating, there's a loss of power, engine bucking, popping,etc. After the rebuild, the car didn't start because the mechanic didn't unlock the car with the remote but proceeded directly to cranking the engine. In addition, the security relay wasn't actuated for starting to take place. Electrician did some wire cutting around that axis which he said was corrected to factory, opened with a remote before the car started.
Fortunately, after everything, the car started again. But there was still an intermittent misfire. What the car owner said was that, 'even when the second mechanic did engine rebuild, the car still misfired. Until he personally bypassed earth from the COP wire to the solenoids very close to the fuel injector often tightened with 10mm knot and depicted with blue and green colors on the picture. Car owner verified that the reasons for the misfire from both mechanics which still prevailed, was due to the solenoid valve that wasn't opening. That's why when accelerating it experienced a loss of power, similar to that experienced by a faulty fuel pump.
After gear oil replacement and test driven by the second mechanic , smoke started emanating from the engine bay. Precisely, from the fan relay that the car owner connected by himself. Within few minutes, the car shutdown by itself as if fuel is finished. As he tried to restart it, the car refused to. Infact, when the ignition switch was turned to Acc/ ignition position, battery and fuel light was not displaying in the dashboard/ instrument cluster. However, during cranking battery light glew faintly and start. But when throttled, it would shutdown. Electrician verified and replaced the alternator diode with a new one. When Ignition switch was turned to Acc/ ignition position, the battery and other lights came out brightly but when cranked to start engine wouldn't start again. Sadly, it still wouldn't start.
I tried to scan for DTC codes, but my scanner wasn't communicating. I checked all fuses, power and ground at obd port, those checked ok. but my scanner isn't compatible to read CAN network. there are only 4 wires intact for the obd2 port.
Furthermore, I added fuel through the intake to the engine, no change at all. I checked for spark and injector pulse. These things weren't present. But there was power to injector with just the key at ignition or ACC and COP had 1 ground and 1 power as usual.
Electrician from that garage, who also worked on the car said that he sniffed burning smell from the ECU, however personally I didn't when I went to start the car. I don't know how certain that was. Hence, I pulled out the ECU to a laptop board engineer to test the components inside. He said: "everything looks ok and test fine, however the IC he doesn't have the right tools to proceed with the test. With the ECU removed battery connected, Engine light would come ON. with ECU connected check light still comes ON.
Before I left, I checked the MAF sensor 5 wires and noticed that 3 wires were earth instead of 2 and 1 power; no ignition current/ power was available for the remaining 2 wires.
Please, what should I do to start the car?
What is the difference between constant ground and signal ground?
how can I find out what the output voltage is supposed to be? Its at 0.65v without me blowing air into it. I Can get it to 1.5v if I blow at it.. I don't know what readings it's supposed to have
I know this is years later but can we also look at g/s on a code reader to see if MAF is bad? I was told my MAF on my 6 cylinder should read between 5.0-6.0 g/s. It’s reading around .5 g/s. Any help out there?
G/s is grams per second
I have a scanner that shows 0 volume of air flow by the MAF sensor, so does that mean the sensor is bad?
Would the procedure be different for a 5 wire sensor?
Is there is a Risk using multiplemert?
I did this test and when i back probe MAF I get matching voltage as battery around 12.2 when car in on positions. When I start engine I get 13.3 to 13.7 volts. Then when i rev it goes up
how come you didn't rev it higher? I revved mine until I hit where my engine was stumbling and the volts jumped from 1.8 to 4.0 and everywhere in between erratically.
your vary nice man aur techer
R&W! I'm following your method and am getting -12.00 something BUT MINUS!! is this correct??
Switch the cables.
But this engine doesn't want to stay running. I'm checking all the wire connections. So far everything tests okay, as far as I can tell. I tried running it without the MAF connected. It wouldn't even start. Right now, it starts, then dies, like it's missing really bad.
How can i test the wires if they’re not accessible? The connector from the cars harness is covering it, only a hair thin pin and fit in the connector.
I did the exact same think but mine is stuck at 2.2 it doesn’t go up or down is that my MAF bad it’s a 2005 gmc savana 2500
You do a good job explaining exactly, but you don't show how the leads are connected throughout the entire video. Please show the whole set up otherwise beginners like myself can't do it. Thanks.
hey what state are u in?
Hi dear have u ever had any maf signal wire showed 4.3 volt at idle then goes down smoothly like 4.2 .4.1 at higher rpm I can't figure it out power and ground is okay its 94 camaro z28 I drives better without maf thnx
Did you end up replacing the maf? My chevy is doing the same
+Kourtney Adams no i did not .i bought a service manual and it says look for herts signal frequency not volt so it was ok
I didn't understand at all . My car MAF sensor was indicating 2.2 v when revving engine up . And 0.1 when ignition OFF . No explanation at all why ?
The engine check light came up on my car, had it checked with obd sensor and code indicated P0101. Had MAF sensor replaced and light appeared still. What to do after this? You could tell every one to check for leaks, cracked intake boot, vacuum leaks, clogged or improperly installed air filter, and many more that cannot be mentioned here. Its alot of diagnosing for this horrible CEL code. Take it easy .
hey why not use the main ground instead of using the sensor ground?
how do you test the last few wires if the car does not start ?
my sensor and throttle body are brand new i cant make car idle it shakes and dies my codes are poio2 po113 please help thank you
Forward pin test is fine,but rear test is better,no need to take apart
Which wire we connect prob and start Engine
Can a bad MAF sensor cause a rough idle but not make a code happen?
yes
Dudes. Thanks
how to check maf sensor pulse in tester while engine running?
Can’t you just test the maf sensor by using a decent obd2 code reader instead?
What happens if i have more than 4 wire setup?
Shouldn't it have a 5vote reference signal?
which are the wires that you backprobe?
He said there are (3) Wires...
a) constant 12 volt feed
b) ground
c) signal
He attaches the leads to the b / c
DangerDaveFreestyle b&c ? I thought it was a&b ? I’ll go back and watch again. If I’m wrong then that might explain why I was only getting like 3.8 volts and it never changed in voltage. He only shows you one that is good , what if like mine it only showed and stayed at 3.8 volts? If I did it right could this also indicate that it’s bad by doing this?
Ok, I did it wrong I believe. Went back to watch it again and he talks about identifying the constant voltage wire in the ground and then he says we need to test the remaining two wires which in his, it’s the two Signal wires. Now that makes sense to me. I guess I’ll be checking it again tomorrow.
I don’t think you actually said which wires you ended up back probing when you started the car.
I believe he probed the signal wired coming from the sensor. He determined which 2 wires are the suply power/and ground, and those values shouldn't change if everything is working properly. So you just need to measure the power out put from the sensor to the ecu. I hope this helped.
My car shows at the pins 12.55 Volts is this normal???
U cked 4 wires, when attaching the clips; which r the remaining 2 wires
+James Betts Probably the thermistor-circuit that senses intake air temperature.
Very Good!... #119 ✝ {5-25-2022}
Nice.
Very easy.
Mine hase only 3 wires :/
Hino p11c troubleshooting wiring ecu
I thought this was going to be a digital maf sensor.
Great
Have that same dmm
Double jointed thumbs freak me tf out 😂
My readings go down and my power is only reading 5v,
Live data scanners have also gotten cheap!
🎉🎉🎉🎉🎉🎉
Mine has 6 pins :P
If you have a 6 pin connector and six wires going to the plug also your MAF sensor has a air temperature sensor combined in the MAF. Some models have the sensor mounted on the air box with two wires going to it
where the air filter is located to monitor air temp as air temp will also play a role in how your computer adjust for fuel mixture also.
all you need to do to test M.A.S , first start the car, let it idle , and unplug the MAS wires connected to the sensor, if the car stop your sensor is good , if the car keeps running your sensor is bad. it takes 3 second ... No need for this elo tester
10 4 lil fat buddy
That only works on older cars. New cars still run. You hear a slight rough idle from the car for a second then it uses the computer settings to run.
You only tested the harness but never actually tested the SENSOR like your title states.
Did you have additional steps you could recommend?