Mercedes C230 Mass Air Flow Removal (MAF) P0170 (M271)
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- Опубліковано 24 сер 2024
- Removal procedures for the 03-05 1.8L C230 Kompressor. Removal of the mass airflow sensor requires the removal of the air cleaner box.
The MAF is commonly changed for P0170 Fuel Trim Malfunction MIL
Thanks this really hellped me (P0174). Problem is both the underneath the air box hoses are already both changed (can tell by them using zip ties instead of clamps)and neaither has any defects. Imma change MAF since I have one already and if thats not it then I guess downstream O2 sensor? Then Im kinda screwed outta idea after that. Thanks again.
Yea that is how I eventually fix the rich condition (down stream O2 change). If you have a extra MAF, definitely give that a try. If you have a OBD scanner that has live data, compare the data readout from the 2 MAFs, if they are similar its unlikely to be the MAF.
I did notice my downstream O2 producing strange responses to changing engine load, and that is what clued me into the downstream O2. Plugging in Mercedes DAS finally told me it was a defective downstream O2 (for some reason, regular OBDII did not pick up the code, likely because it was still sending voltage) with a MB specific code.
Speaking of o2 sensor, my upstream measures 2000mv when I start engine, but I can’t fix it even after replacing the upstream.. wondering if it could be maf sensor
Instablaster...
Very good instructions as to how to wriggle out the air filter box.
Workshop dealerships hate DIYers. They think they are the only ones who are capable of doing such things.
Periodic cleaning of MAF sensor and throttle body (which do not take up much time) will reap benefits in the long run.
Thank you very much.
+Ronnie Tan
Thanks! Yep, learning how to remove the airbox on the M271 is really helpful. That thing is in the way of many components in this engine. Speaking of MAF removal, I might clean it again.
Thanks. Great video. This helped me change that $12 (£10) hose and yes it had a split in it. Wish I'd bought the rear hose as well (mine was soft and collapsing) so I ended up doing the job twice!!
I know you recommended it but I came to this video after I'd started the job. Would also recommend getting hold of a "Flexible Long Reach Locking Hose Clamp Removal Pliers with Ratchet Tool" to remove the air intake hose clamp. Makes a very awkward job so much easier. (Although I noticed you had a normal hose clamp). Thanks again. Brilliant.
The air box has been a pain to remove. Going to try the putty trick. Ingenious solution !
any tips? struggling to get it out myself
hI just came across you video which was great in showing how to do this job, I am a woman doing this but I am determined to learn everything I can to work on my car myself. I'm a very determined person! I always say who needs a man when you have youtube videos! just kidding don't send me nasty messages! getting back to my problem, I have a 05 c230 kompressor and i'm getting error code PO171 faulty air mass flow sensor, so after watching this and having all the tools on hand I'm going to attempt this myself so I will let you know how this goes! we women need your videos!
Outstanding video. I'm trying to change the crank sensor on a C230 with this same engine. I can't see it nor feel it, but I reckon after pulling all this stuff off, I can at least feel back there and hopefully change that part. I'm really hoping I don't have to further disassemble it to access that sensor. Your video gives me hope.
Crank sensors are behind the plastic part in front of your engine.
Easy access!
Most helpful video on getting the airbox in and out. Thanks for this.
This is a great video. However if you look at MAF sensors for sale, they now have only two fixing points - at 10pm and 2 pm. These are easily removed without having to remove ANYTHING else. Once the two screws are out, there is enough movement in the intake pipe ( only need 0.5 to 1.0cm) to remove the MAF sensor. Very quick and easy. However this only addresses the MAF replacement, not the other pipes mentioned.
This is the same as my w203 c180 2006. Thank you.
Top draw Ste, thank you very much indeed, I used this today to remove my air box.
Well work investing in a long reach hose clamp pliers if it is the first time. Glad to see you have modified and improved this Germans car! Bravo.
Best wishes
+cheshire smile
Thanks! Worm clamps definitely does make it easier to remove the air box. I can also understand why MB used those large pressure clamps; they are so stiff that it wont loosen up like warm clamps could. All of this ensures there are no air leaks downstream of the maf. I periodically check on my worm clamp to make sure its still nice a tight.
Hi, just used your video to get an idea of the reality of how the MAF is fitted (in a C200).... All content was very helpful, I knew removing the Pipe clip would have been a one-way-ticket, so I found an easier way..... Removing the oil Filter gives you a direct straight access to the bottom 3rd screw, feeling blind of course, but was totally possible. there is enough movement in the plastic manifold to slip the sensor out as well without removing the airbox. Replacing the screw I had to use some tape to stick it to the driver because I don't have magnetic tools..... We realised the sensor in already new so the fault must be somewhere else.... The ECU (large) connector is contaminated with oil (as you said to look for, I should have looked 1st, me idiot), I will have to get this cleaned out on Monday as I don't have a strong enough airline to blast out any cleaning agent/oil residue. Thanks again
I love your videos and really appreciate the work you put into it. One thing that I found made this job much easier was to disconnect the braided steel fuel line - Only takes a minute and makes getting box out and in a lot easier. Just depressurise using schrader valve at front of fuel rail first.
Thanks for the 2005 Mercedes Benz c230 k video cause it's not easy trying to find videos for DIY Projects, thanks again and I have subscribed to your channel,, keep up on your videos.
Thank you. Clear instructions, I removed this to replace the 12$ hose. Now I'm trying to remove the supercharger to get to rest of hoses and replace those. I do need some advice on how to remove the super charger. Thank you
Thankyou so much!! you're a life saver. I will replace the MAF sensor now it doesnt seem too complicated, i did replace the so called "$12 hose" without removing the air box. It was a huge Pain..
You're welcome. Make sure you have all the supplies before starting! Good luck.
You don't need to disconnect the battery to replace the maf you're already unplugging the sensor
Got my mass airflow Sensor from vehiclevalueparts for cheapppp. Never again will I buy from a junk yard or dealer.. Great video by the way!
Thanks! Mercedes sure knows how to frustrate DIYers with that air cleaner box.
How the hell am I supposed to remove that clamp down there. I tried various tools, but can't even align it on the clamp, because its in such an angle that there is no room to turn my Tool around.
So I have to order this special clamp remover it seems. Goddamn mercedes benz.
Thank you for this helpful video!
I got a P0171 faultcode and the engine is running ruff on idle. I tought let's do a smoke test but detaching the MAF looks like a PITA. But with your video i got a few good pointers how to remove the airbox.
Wiren Changoer thanks! My issue turned out to be a defective downstream O2 sensory that never threw a OBD code. I brought a Xentry diagnostic system and that showed me the Mercedes specific code, saved me a ton of headache. I now sell these diagnostic machines for $520 shipped if you're in the US.
Did you ever find the cause of P0171? Were you able to smoke test? Any pointers? I have same code and would like to smoke test to look for leaks.
Great video and worked well, was able to get a large vice grip to loosen the clamp on the lower outtake as you state was the hardest, thus will go with the hose clamp design. Thanks for the assistance,,,good job. Now on to the oXY sensor downstream...no bigge there..
Wow... not easy huh. Planning to do this... as I have lean mix code. Obviously one just can't figure this out unless seeing it done. So big thanks in advance!
It's definitely a hassle the first time, but after the first it only took 15-20min to take out the next time.
Same as w203 2007. Man, such a long job. In other cars its a matter of removing a couple things. I'm not looking forward to doing this lol
Please My engine stops when the temperature is at 90°
Thanks a billion man ur video helped out alot
Hell yea it did! Had to remove camshaft supprt the set new gasket. 5 hrs later im ready to reinstall everything
Thank you for posting that video. Have you changed the hose and PCV valve under the supercharger yet? I have not found any videos on that procedure.
I have a p0171 only, I changed the fuel filter, upper 02 sensor bank 1,spark plugs and a little German fuel cleaner, the car runs like a champ full boost, but that freaking p0171 code pops on after a couple hours of driving after being shut off and back on... smoked it can't find any leak...
Jimmy85 Go
you need to check live data and see how the long term and short term fuel trims are acting. You have a scanner that will tell you?
i have the exact same issue on my 04 c200k, p0171 car has been to 2 different MB dealers and a local European specialist in my area, none of them can find anything wrong. smoke test showed no vaccum leaks, both o2 sensors replaced, hoses under airbox replaced, MAF replaced, plugs, filters, cam sensors replaced. CE light only comes on when idling or below 15kph. long term fuel trim sits at constant +18 when cruising and spikes to +21.9 when under load short term fuel trim looks fine
Thank you for the video, very informative. The $12 hose though, do you know what the part number would be?
Yo so my hose above the pulley belt by the engine has cracked n has air coming out from it not sure if I should try n fix or sell it before gets worse not working at the moment or I would of fixed the problems on it
Is this why my car idles ?
throttle body actuator c230 is the title of the video.
The last time I moved it it shuddered so I have not dared move it again until I fix the problem. When I start around the air box shakes then after about 30 sec a minute it sorts itself out and is smooth without the Rev gauge moving, everything is fitted correctly I triple checked on removing. I have oil around both of those magnets on the front, is this then the leak that's affected my loom and injector connections?
The only codes I have are those to and both are saying bank 1. I get cl and ol faults, and have these readings at idle for trim- SFTF -28 at 3000 rpm it is at 0. freeze frame its 25.0
LTFT does not move at idle or rpm that's 15.6
Very good video, thank you. I have to do mine.
Great video I have the nice p code , maf sensor reading low a d fuel bank 1 etc , I checked air filter and it’s clean so I’m going to have to take the box off and check maf & vacuum pipes , I noticed on my obd11 that my maf readings where 0 , but if I moved the connector the maf readings started to register around 2.78 odd as if there’s a connection problem with the plug??? Is this due to the maf being gone ??? It’s a c 180 kompressor 2005
hey ste.l I was wondering what u would think about my problem I have the 2003 c230 k my problem I figured was the o2 sensor I was getting codes p0172 p0136 and p0137 so those codes told me it was bank 1 sensor 2 so no problem changed the O2 sensor there was a little bit of oil inside the plug where the O2 sensor connects so cleaned it and changed it I cleared the codes I never got the P0136 and 137 ever again but then later code p0172 came back up and then went away on its own and then came back up also with the code P0170 so damn it I don't know what to do car runs smooth always just not great gas mileage and recently if I floor it it will want to misfire I get like a spotter until I turn the car off when I turn it back on it is fine it's almost like it floods itself then after restart it adjusts to normal. also notice power loss for sure so just wondering do you think that would be the MAF or still problems with that O2 sensor??? seems like somewhere it's just mixing the wrong gas and oxygen levels...thank you for reading this!! anyone have any ideas?? And also when I installed that oxygen sensor I tried to fill the 4 wire holes so no more oil would drip in so I almost think it's not the oxygen sensor again at all just thinking maybe when it was bad it messed with the MAF sensor??? pissing me off the car only has 89,000 on it!!!
wes p
Hello Wes, always happy to lend a hand.
1) changing the downstream O2 was definitely a good start and seeing that that p0136/7 code is now gone suggest that cleared the issue
2) one thing I want to ask is, were they OE Bosch sensors?
3) it would still potentially be the MAF. One key thing you need to monitor is the car's long term fuel trim (ltft) and short term fuel trim (stft). If you don't have a scanner, i suggest getting a cheap one.
4) Poor gas milage is exactly the issue I had. I also had a very rich smelling exahuat, yet my my cars computer kept telling the injectors to spray more fuel (eventually it was a misreading down stream o2). This leads to another problem, unless you are monitoring how your o2 sensors reads on a scanner, you don't really know if all the problems are fixed. A o2 sensor may not throw codes but still produce incorrect data for the on board computer.
I suggest monitoring what your fuel trim levels are and reporting back.
+Ste .L. awesome thank you very much for the reply and yes I do believe for sure 99% I got a Bosch O2 sensor and like the problem you had exactly what you said I can smell super rich exhaust it like blows you away when you are standing behind the car LOL that's happening now I just changed it a few months ago so I was hoping it didn't go bad what should the reading levels be on the scanner tool I do have one and that's the code it's throwing p0170 and p0172 and one of those it does say fuel trim for the code I think it's the 170 when the sensor was bad before I changed it it never ran bad at all just the check engine light would come on now when I floor it or give it a lot of gas it kind of gets too much air or gas and wants to misfire that's the weird part so I didn't know if that o2 sensor would make it act like that and the o2 sensor I changed was after the catalytic converter not the one I can see right down in the motor where the exhaust starts is that the same one you had problems with? thank you so much again for the help
+Ste .L and I was hoping maybe having that super super strong exhaust like crazy would give a hint of what would be wrong either MAF or O2 sensor
The one I had issues was indeed the downstream post cat sensor, but i was able to identify it with Mercedes DAS. Yes, a overly rich mixture can cause misfires especially under heavy load and it can't combust all the fuel.
A rich exhaust can be caused by many many things, including a false lean which tells the computer to dump more fuel needlessly. Were you able to get LTFT and STFT data?
Thank you for video.
How fucking complicated jesus christ
Thanks. Great Video. I am trying to find a link to the remove and replace the CPS
I have a 2003 c230 kompressor and when I first start it , it runs and Reva perfectly but as soon as I do a good pull on first gear it starts to misfire what would cause this ? It's not the spark plugs or the coil pack
I had similar issues with my own m271 engine. Drove relatively fine, but would misfire and buck under higher loads or near WOT. Unfortunately I never discovered what was the cause of this issue. I suspect there are a multitude of reasons why this could happen. You've ruled out spark, are there any other issues you are aware of with the engine? Fuel delivery, valves, etc. These DI engines are very prone to gunked up intake valves, and a clogged/leaky injector can show problems under higher demand.
Do you have a Xentry/SDS scan tool?
@@SteU4IA I do have a scan tool yes
Sorry for late reply. A basic obdII scanner or a Xentry scan tool? Any codes?
@@SteU4IA yeah got a bunch of codes a misfire in cylinder 4 is the main one
If the others aren't major, the isolated cyl 4 misfire does suggest the issue is within that cyl. Investigating the injectors and valves in the cylinder is probably smart. A compression test of that cyl is probably smart as well.
What are the expendable parts for this job? Just that hose you showed the part # for?
excellent video. makes things a lot easier now. can you tell me where the knock sensor is located. thanks
I don't recall off the top of my head but I remember there were several. Some at the front and rear of the engine.
Thank you I'll check the downstream O2 sensor, I've checked the upstream and it appears to be clean and oil free. I was trying to get away with not having to jack up the car on stands but I guess the oil needs cleaning in the connectors for the sensor and get a new sensor. Both my camshaft sensors have no oil contamination at all and I'm not sure if this has been looked at before and change but they never sorted the rest of the contamination. My leak appears to be coming from the fuel injectors so I'm going to check the o-rings and clean all of the oil up around the injectors and in the connectors, there was a lot of oil there. Why do you think my rattles on idle for a minute or so around the air box area?
- one thing to note about sensors, like oxygen sensors, is they may look clean but may still be failing. Likewise, they may be oil contaminated but still work fine. For whatever reason my downstream o2 did not completely fail (thus no downstream o2 obd2 codes), rather it was just reading a little off (only mercedes specific code was thrown)
- do you mind going for a normal drive cycle while monitoring your fuel trim? let me know your STFT and LTFT at idle (at a stop light) and while accelerating + while at steady cruise.
- as for the rattle, is it only present when engine is cold? or present all the time ? maybe make a video of it and post it on UA-cam?
- it could be a loose bolt you left while removing the MAF or getting to the injectors. the MAF and air box unit should be tightly bolted to the engine and any shaking and rattling should be controlled by the engine.
- I also had a tonne of oil in my first injector's connection to the harness. in my case, oil from the magnet cam adjusters (the 2 silver things at the front of the engine) wicked oil to this location. I did not have problems or issues with this but I still cleaned it up.
btw do you have any other codes?
nice video have to remove the box in a few days, really nice tips here.. thx
Thanks. Good luck and let me know if you run into issues.
didnt have major issues removing all that stuff i had to.. even had to remove the supercharger for the "12$ hose" but it was worth it.
andisetsfire
Great! Did you make a video of the SC removal?
no man i didnt... had to figure out how to get that stupid thing out there first so , no time for a video :D :D
Trying to get at the crank shaft position sensor.. Is it necessary to remove the MAF to access the sensor?
Great video! Very detailed!
ste .l i was also told its a vacum leak under the maf. i have also read that it could be a o2 sensor. please let me know your results. Thanks
+Miguel Vargas
Hey Miguel, i fixed the problem and it was indeed my downstream O2 sensor. It didn't throw a code for the O2. Just P0170 and P0172
Hi there thank you for this video, i have a 2005 w209 clk 200 k, engine looks the same as yours, i have the p0172error so starting with the MAF, im hoping to clean the sensor and hopefully solve my problem!
Stevie Wildey
There is a lot of talk on forums about cleaning the maf, but I have yet to see consistent results with just cleaning.
a lot of people initially cite the maf as defective whenever trim codes (rich or lean) arise, but I think a easy way to pin point the maf is to use a scanner and monitor the g/s airflow the sensor is reading.
my problem actually turned out to be a misreading downstream o2 that was only discovered by running DAS on it.
Ste .L thank you for your help, your right its only a guess as i have a fault code reader and its putting out that code so i dont know for sure, i dont have any other testing equipment so not sure on what else to check? Maybe i should look at the o2 sensor? Thank you for any help
Does your scanner allow you to read live data stream likes Long Term Fuel Trims (as well as short term) [LTFT & STFT)?
If not, i suggest getting one of those ebay bluetooth OBD scanner and hooking it up to a mobile app like Torque. I was able to monitor a lot of my trim values and its reaction to load, etc. It helps with diagnosing.
Ste .L affraid not, i has battery issues before any codes and the cel, ive changed the battery and cleared the codes and drove for about 45 mins with no problems will keep an eye out to see if it returns! Checked for codes after the drive and got nothing not even pending? Batterys can cause all sorts of problems so fingers crossed it was that which was triggering other issues as it bought the check service b and esp failure, which sprung up with the old battery not holding charge
That is very possible that it all stemmed from the battery, however the car takes several days, a 100+kms, and several cold starts to monitor the entire system for faults. Check your readiness codes, if they are all ready and you still have no CEL, you might have figured out the issue.
Good luck.
Would have been a fantastic video if you just turn the Flippin radio down or turn the radio off and if you would’ve had your camera pan just a little bit more out for us none mechanics this video would’ve rated a 10+. Thanks for the help Ace!
Excellent, would be better without the distracting music in the background. You did such a good job.
Where is this engines IAT sensor located. Is it part of the MAF or seperate
Really helped me thank you so much!Just one thing can u clean the connectors filled with oil with maf sensor cleaner?
anna maarraoui
Thanks! You can use electrical contact cleaner since I believe that is less expensive. But MAF cleaner works too.
I’m having turbo boost sensor problems please help 05 c230. Is there 1 or 2 sensors ?
Hi. Is there no way to replace just the sensor without removing the housing or is it all one piece? ie moulded. Thanks.
Simon R unfortunately, like you said, it is a single molded unit.
Ste .L ha. Typical!
they say is not good to leave the ecu without a power supply from battery. is that tight?
I don't think that's true. I've unplugged the ECU multiple times without issue. You do want to unplug the battery first however so there isn't a surge of electricity. (Just to be safe)
ML 350 P5410
The video stopped at the most critical part of the job in my opinion. Getting a new rubber around the tube when re inserting the box is nearly impossible, and then to try and clamp with the extended clamp holder and get the proper seal is bullshit!
I think this is the reason I now have a p0171 code running lean as a result of air leak. Too much air in the mixture
Add a little bit of oil around the airbox piece, wiggle it a bit and it will slide over the hose.
Cars N' Boba thank you so much for your reply I will try
Thanks for the video. I understand the worm hose clamp tool. But what is that skinny tool you used to tighten the clamp nut called? Instead of using a long flathead. Not sure if the video was cutting out or I missed it. Thx.
MrMrdynes
Hi, it's called a flexible driver.
Do you have a part number or a link to buy a new one?
Hi, I am getting error codes:
P0130 - O2 Sensor Circuit Bank 1 Sensor 1
P0410 - Secondary Air Injection System
What would cause these errors and what needs to be replaced?
Thank you in advance for your help.
hook your car up to the obd scanner and see if you get rich lean response under sudden acclerstion and sudden release of gas pedal.
p0130 often, but not always, points to the pre- catalytic converter air fuel ratio sensor malfuntion (it isn't a O2 sensor, it is a wide band air fuel ratio sensor specifically).
does your exhaust smell rich?
I have Misfire on cylinder 2 after new harness ecm injectors coils and plugs ? Is the head just bad? then it just popped bank 1 too lean
Pressure test ok?
Mine is P0172 engine check always on. Lost of supercharge power, acceleration picks up very slowly and when AC is turn on the idle fluctuates up and down likes going to die. Does what you done help?? One guy replace O2 censor nothing improve on his car who have the same issue. I took to the shop they told me the Throttle body need to replace it is bad and will cost me $1000 plus labors. Could they be right about the throttle. I need some good answers?
You can buy a good used throttle body for cheap and do the change yourself, watch my TB removal video.. its fairly easy job.
ua-cam.com/video/iNwkpy4Tb6A/v-deo.html
2 people can have similar symptoms on a car, yet have totally different causes. I suggest going to a shop that works on Mercedes and ask them if they can scan the car with a Mercedes DAS system. It can read codes that OBD scanners cannot.
Hey thanx for posting!! Fknfantastic!
+sever 13 clouds
Thanks! hope it helped!
Hi there is in my car light engine bulb working error code is p170 fuel trim bank 1
Yep, that is one of the codes I had. Many causes from MAF sensor dysfunction, to vacuum leak, to O2/Air fuel sensor issues, etc etc
Can I reuse the clamp or will removing ruin it? I understand you wouldn't do it but are there any pitfalls to replacing it with cable ties?
Simon R the clamps are reusable. If you don't pull the zip ties hard enough, or if the ties don't clinch down hard enough, you risk a vacuum leak.
Ste .L thanks for reply Ste just finished it reusing clamp. Bit of a ball ache replacing unit kept bending rubber intake over with the unit back pipe but suddenly all slotted in. Your video was invaluable as garage quoted £400 and I spent £90 including clamp tool. Very grateful!!
Simon R
In really glad it has helped so many people. If you plan on keeping your MB or have other MBs in the household, I suggest getting a clone Mercedes DAS Xentry diagnostic system. I was able to pin point my post-cat O2 sensor with that tool in a matter of minutes. I spent 2 years and hundreds of dollars chasing the problem and it was we'll worth it.
Hi, after changing The hoses under The box and The air mass sensor, my car started to run very bad, no fault codes at all. O2 sensor seems okay when testing. Any ideas?
All clamps are hoses are on properly? It's very likely you forgot to reconnect a vacuum hose and there is a vacuum leak somewhere.
@@SteU4IA yes i have checked it 3 Times. Tried with The start spray and cant find any leaks. Also when i put it in drive or reverse it almost dies and gets all jumpy. It did not do this before.
I have code P0102 does that mean I just need to replace MAF i have that code and misfire on 2&4
ASAP Robbie bro i had the same did u manage to fic it by any chance?
hey will this cause fans to run hihh
Hi Mate!
Thanks for informative video. Would you mind to suggest $10 hose part number please. Thanks in advance.
+Mohit Bhardwaj
Should be this: A203-018-12-82
hi again
I've changed the downstream sensor and cleared the codes. now I'm getting still a slight rev on ignition for a few seconds. it also nearly stalls itself sometimes and there is still a strong smell of burning fuel,
only code showing now is p0172, p0171 has gone.
any other things I could check that maybe the answer. if the MAF sensor connector had a ton of oil in could it be broken shall I change? cheers
Oh wow even the MAF harness had oil in there? Do you have the pig tails installed where the cam magnets are (front of engine)?
Did you ever do a LTFT and STFT check? Interested in knowing the values.
Also, are your MAF sensor data (g/s i think) in range? Monitor that with a scanner and drive around. Any vacuum leaks?
Ste .L I've got:
P0172
CL FAULT FUEL SYSTEM 1
SHRTFT1 0.0 AT 3000RPM 0 - 27.6
LONGFT1 15.6
each time I reset the codes it comes back after a few minutes. I reset and discounted the MAF to see if it would show up, but no code returned. I've noticed the connector for the MAF sensor on the loom side might be missing a contact there's four of the female pins and the fifth one is empty is this meant to be like that?
Ste .L I haven't fixed the oil leak yet I want to clear the code before I buy the parts for the cam magnet leak, mine appears to have leaked from the sides of the magnets not sure whether to buy new ones or just change the o- rings and use sealer then get the extensions, what's best?
The MAP sensor that is attached to that airbox, does the vacuum port of the sensor connect to anything? because I took mine off to inspect it, and other than the power connector, the air port on the sensor was not connected to anything... PLEASE HELP>>>
Anthony Mccoy the Mass airflow sensor has no vacuum port attached to it. it is only the eletrical connector
Im actually talking about the Manifold absolute pressure connector that you unplugged in the video, I actually unscrewed the 2 screws from the air box, removed it and noticed that the air port on the sensor didn't insert into the body of the air box, and no hose connecting to it, www.ebay.de/itm/MAP-Sensor-Luftdruck-Ladedruck-A0041533328-Mercedes-C-Klasse-W203-S203-/111361745920. this is the part
Of course the electrical connection is here, but underneath the air port goes nowhere.. so confused if that is normal. Reading just normal air pressure or is supposed to connect to a vacuum hose..
Barometric pressure sensor near the opening of the airbox
Anthony Mccoy
Oh I'm sorry, right the Manifold absolute pressure sensor. I noticed the tube open to ambeient air that's part of the sensor, mine did not connect to any hose so your set up is normal as well.
can you send me the link or name of the tools to remove the hose clamps ,the one you bought on ebay.
search flexible hose clamp pliers on eBay or online.
first hit on eBay is a $13.55 model that is essentially what I used.
Hello I was wondering if you could help me, I have error codes p0171 and p0172. I have taken off and cleaned the MAF sensor, which didn't look dirty, but I have oil inside all connectors of the loom and badly around the four fuel injectors. The camshaft sensors have no oil contamination and I have managed to clear most of the oil so far. Not sure if inside of MAF Is bad as you can't get inside it on the m271. Not sure if I should change the MAF as its reading between 4.5 and 5.5 g/ms on idle. I have cl and ol faults. Starting it revs on its own bad idling then it comes down to steady, during this process it seems to shake around the MAF sensor area.
Cheers Kevin
interesting, you have both 0171 and 0172 codes (too lean & too rich)?
I don't know if you saw the captions but I actually figured out my problem and it wasn't related to my MAF, rather it was my downstream oxygen sensor (yes, you read right)
I too had oil in my harness loom. make sure you get the pig tails installed at MB (MB Canada installed them for me many years after I stopped using their service and the warranty ended). give your local MB a call. The lowest part of the loom is the connector for the upstream AF sensor and downstream oxygen sensor. These are under the car and possibly the oil fouled my downstream O2?
what I really want to say is that many people mistakenly focus on the MAF, including myself. I was fixated on the MAF so much that I became proficient at removing it. I monitored my MAF reading just like you (i got similar values as you) and in the end it WASNT the MAF.
The only way I was able to diagnose this was with a chinese SDS - xentry diagnostic tool that directly pointed me to the downstream o2 problem (code literally said downstream sensor had issues). Many mechanics and DIYers understand that the downstream o2 has no influence fuel trim but they are wrong it it 100% has an affect on fuel trim (and thus throwing FALSE fuel trim values and codes)
let me know if you have questions and I'm more than happy to help and guide.
I want to note that my engine also had a slight rough idle (+/- 10 rpm switching rapidly) when I was trying to figure out this car.
i changed my maf, spark plugs, and engine mounts which seems to have lessen the feeling of the shaking engine but it did not clear the codes. only thing that stopped the rough idle was changing my defective post-cat o2
can the MAF meter alone be removed/replaced without extracting the whole sensor?
no, I think you'll have to break the casing. Puting it back would cause an air leak.
Oh ok. Is that because the meter is part of the casing and not bolted on ?
correct, it is an integral part of the case itself. The entire case must be unbolted and removed from the intake piping....it just sucks because 1 of 3 bolts holding the case onto the piping is impossible to reach without disassembly.
My c180 w204 is similar layout, is it possible to take Out the map sensor without removing airbox?
Just to confirm, you want to remove the MAP or MAF sensor?
Hi my friendly video creator, I just want the map.. I can see the map
The only map I see is beside the electronic board, kinda underneath the airbox.. My car is a c180 w204
The MAP sensor is bolted onto the plastic manifold just before air enters the engine. I believe the airbox is first removed to gain access to the manifold underneath, but yes, once you have access to it you just need to unbolt it and it comes straight out.
Thanks a lot mate, was hoping I that I can take it out without removing the airbox, I Guess there are too many things blocking, not very possible
can replace the airflow sensor it self?
W203 C180 Petrol
raed fahd
this is the only way you can change the MAF.
Maf unit or just the sensor
what part number is??? MAF? I have the same engine c230 compressor engine 271 948
Would this resolve po172 ecu code?
I have the same issue along with p0170. Every forum says it's the maf, but I changed mine with a new MB MAF from the dealer and it didn't fix it, unfortunately.
I'm still chasing down the issue. what's odd for me is my fuel trim is +12 which means the ecu is telling the car to dump more fuel. Yet, my issue is a rich exhaust.
I have a slight hunch it is a vac leak because the fuel trim does normalize with acceleration. But, a shop said there was no leak.
I also have a hesitation (misfire?) When the engine is cold and I'm going to a abrupt stop.
I think I'll do a compression test next.
+Ste .L Look for vacuum leaks, i.e. broken vacuum lines or connectors, or other components. Get the hand vacuum pump to test components and you can use propane gas to find areas of the engine where vacuum leak is present.
+Alex V.
Thanks for the suggestion Alex. I do have a vacuum tester (Brake bleeder tool) and I've tested a few things (EVAPs solenoid, etc). I actually had a shop do a smoke test on my car and they could not find a vacuum leak.
My fuel trim is pegged at +14 (LTFT). This would suggest a vacuum leak (unregulated O2 in intake = lean emission = ECU dumping more fuel). What i find odd is my exhaust smells really rich and I feel that the ecu is dumping fuel for a false lean.
I've noticed my exhaust pipe is 100 Celsius hotter pre-cat vs post-cat. This may suggest a clogged CAT and I'm not sure whether the pre-cat o2 is reading incorrectly (poor exhaust flow) and causing all these trim issues.
DUDE you are brilliant. I had a tight original gas cap, once off, tank filled, I got a check engine light on my C230 #WTF ... Auto Zone lent me a thingy and my code was p0171, Bank 1 lean etc. / After buying a new gas cap my light is still on so I'm like yeah whatever I'm going to the whorehouse in Tijuana to have a few drinks
I put a new air filter in it, drove it 40 mi and the engine light went off.
This is the same as my w203. 2006 c180. Thank you.
ste .l i was also told its a vacum leak under the maf. i have also read that it could be a o2 sensor. please let me know your results. Thanks
+Miguel Vargas Hey Miguel, sorry for the late reply it was flagged as spam (?)
Anyways. I had my car smoke tested and they found no vacuum leaks. I've already replaced the upstream o2 (the one that determines trim) and that did nothing.
I'm starting to think a clogged exhaust might be causing my messed up trim. I am also looking into buying a Chinese MB C3 multiplexer and using that to reset my trim adaptation. I have a carsoft knock-off and that can't seem to reset adaptation although it was advertised it could (it reads codes fine at times though).
hey will this cause fans to run hihh
+tymitri stoddard
The radiator fan? Not that I am aware of. I am not sure how the MAF would be related to the radiator fan.
I'm dealing with the issue of the radiator fan running at max speed as well, so I ran an OBD and I got four codes:
P0620 - Generator Control Circuit
P0304 - Cylinder 4 Misfire Detected
P0410 - Secondary Air Infection System Malfunction
P0237 - Turbo/Super Boost Sensor A Circuit Low Input
I haven't devoted a lot of time to fixing this car, because it's my brothers, but I came to a point where I decided it was the MAS causing all of these problems. I'm really not sure, I believe it could be a fuse or relay as well. I'm currently replacing the MAS anyways so hopefully that is the fix.
-Great video btw. It's very useful for dealing with Mercedes where it seems to be a puzzle at every point trying to fix something.
Yes this car is a puzzle, and I think it has to do with that fact that you would probably need the Mercedes STAR/DAS diagnostic system to truly understand the problem at hand.
The issue with using a generic OBD code reader is that it often times produces interpreted codes that only a STAR system can recognize. As a result, you get weird codes that do not make any sence.. which only complicates the diagnosis.
For example, i made this MAF video because i had wacky fuel trim readings and EVERYONE said it was the MAF. Guess what? I replaced the MAF (and made this video) and it WASN'T the MAF. I eventually purchased a DAS clone (chinese copy) and the codes it gave me pointed to the DOWNSTREAM O2. Never in my mind did i think a downstream O2 would every cause fuel trim problems ( if you know cars, you would understand), but it was indeed the downstream o2 and i managed to fix the car after 1 year scratching my head. Further more, i also got a p0410 secondary air injection failure code just like you, and that turned out to be a FALSE code generated from poor interpretation of Mercedes codes using a generic reader.
I suggest getting your hands on a DAS system if you are serious about fixing the car. It is a $300 investment that is easily paid for by NOT buying useless parts (MAF is $500)
ste .l i was also told its a vacum leak under the maf. i have also read that it could be a o2 sensor. please let me know your results. Thanks
what does he mean vacuum leak "under" the maf? literally a leak right where the maf ends? Or a leak occurring anywhere after the maf? if the latter, it doesn't mean much because all unmetered air leaks occur after the maf anyways.
I thought it was the upstream wideband air fuel sensor too. mine was due for a change so I changed it. no difference.
I have checked most vacuum lines and they look fine.
things I have checked are
1. intake manifold gaskets
2. injector orings
3. exhaust manifold gasket ( leak in exhaust causing air fuel sensor to give wrong signal)