This was probably the best explanation of O2 sensors I have seen. Simple, easy, informative and practical all at once. Wish we had this at Automotive Tech school many years ago.
I just want to say thank you for your videos i have learned so much. I am a grandma who's 03 Outback was my grand youngins school bus. But it quit running. So i really love your content, you've given me, a super non mechanical granny the confidence to crawl under my car and try to do some trouble shooting myself. I appreciate what you do & thanks again.
It's been a long time since watching Mr Subaru. Happy to see any Subie fix vid where he talks nerdy and explains fundamentals beyond just showing things wrenched. More how to vids please.
yes, understanding the scenarios that the AF or O2 sensors get involved in, helps a lot with understanding error code diagnostics & source-of-the-problem finding.
Wow ! This was the best explanation of O2 sensors i had in my life...I have a Subaru Legacy 2013 with only 67.000 Klm and i really enjoy your work thk's.
I had one of the older Subaru Outbacks you speak of. An 01’. When I bought it the head gaskets were blown unbeknownst to me. My father in law and I redid the engine and it ran nice for a long time. I live in NY so eventually the rust got to it, put a crack in the actual fuel tank. The o2 sensors did their job -never threw a code. Very informational and well laid out video. I can’t wait for what you have next!
Excellent review, it should be noted that heat is the lowest form of energy. Just about everything generates heat as a byproduct. The O2 sensor takes heat and turns it to electricity, a higher form of energy. That's why they wear out. FYI.
Great stuff! But you MUST now do the follow up on Wideband sensors which wld be pre-cat sensor in almost all Subies since early-mid 2000s ... very important to understand failure modes and can be tricky😱 After a long diag, finally discovered an intermittent failing wideband O2 with a P0030 code on 2004 Forester with EJ251 was caused by sensor element internal resistance not falling quick enuf to meet PCM programmed parameters ... in this case, PCM requires less than 50ohms within 30sec of start or after fuel cut off condition. Very tricky to nail this, but wen u r going to charge a customer $700 for a new part that u can’t return u need to be dead certain. Lets do failure modes, diag and test procedures on wide bands? 😉👍
Coolant takes them out too,the Fords with the 3.8 which had headgasket problems would take them out when the headgaskets blew. ln certain year Dodge truck,the O2 sensor also is involved with shifting of the transmission.Have fixed a few transmission problems in these replacing the rear O2 sensor.Do not top off the gas tank,EVAP system needs space and have seen O2 sensor codes appear from this
I'm working on figuring out the cause of my catalyst efficiency codes so this was great timing. I've long determined the converter is gone, but working on debating if I should swap the sensors "while I'm in there"
Great Video as always. Picked up a used 2015 Crosstrek Premium with 92K mile for my kid. I've been doing various things and this is one I like to do at 90 -100K. Relative to the other Subaru's O2 sensors it's in a pretty easy spot to get to. Replaced the front one with a Denso brand which seemed to be the exact same as the OEM I removed. Right down to the color of the wire coating and wire tie fastener. I consider it inexpensive insurance for the future.
Great explanation. There is a lot of bad information out there on the internet about these sensors that I found when troubleshooting a P0420 code on my '10 OB specifically the many folks saying to replace both O2 sensors. Mine were working correctly and the downstream sensor was telling me that something was wrong thus setting the P0420 code for catalyst insufficiency. I cured that with three treatments of Cataclean and no recurrence some 1000 miles later (I suspect that I disturbed a bunch of crap in the vapor collector when I overfilled the gas tank and temporarily shot crap through the engine). Keep these videos coming - they're great.
I remember giving my tuned rs to a shop in Utah that “specialized” in Subarus to fix a surging issue I had while driving, left it at their shop for three months while I was out of the country and came back to them “solving” it by replacing my charcoal canister. I took it to Colorado for a friend’s bucking and surging the whole way there, under wot it ran normally. I happened upon the Subie Doctor while in Colorado and within ten minutes of looking at it had already diagnosed the issue and put in a brand new oem o2 sensor.
This was an amazing video!! Love that you mentioned the h6, it's so hard to find information about this motor on I think because they're just so solid.
Great presentation. I have a 98 honda Accord that has several O2 sensors die. It also burns one quart of oil per 1000 miles. You are the first to associate oilcontamination. Thanks.
As a chemical engineer who works with these sorts of things, I give you an A+. Excellent job. Thank you for correctly pronouncing stoichiometric. I have heard some folks just slaughter the word. You obviously had to prep for this one. Looking forward to the next video. Thanks. 🏳️🌈
Finally, a most comprehensive explanation on this item. Question though : will the slots in the casing determine the workings.? My supplier insist that the one with the smaller slots are the correct based on the part number. But after installing, engine kinda running weird - like a very short hesitation when acceleration.. Especially when the AC is on.. Thanks for the great video..👍
Extremely helpful info. I’m having an issue right now where my new O2 sensor just doesn’t work suddenly and this gives me a lot to look for when I remove it from the manifold/uppipe.
Talk about perfect timing, I had my 2010 Forester serviced last month for (System too lean {Bank 1}), and the A/F sensor was replaced. A week later the Check Engine came back on with the same code via (Hum by Verizon P017) which turned out to be more than the sensor itself. Intake Manifold Gasket/Fuel Pump/InjectorSeals/PCV Valve. Not bad for a high mileage vehicle 412,433+. I will be doing a complete front-end overhaul by April 2022. In 2023/24 my goal is to buy a new Forester when I retire and hold onto this ole girl...
Don’t have a Subaru but have an 04 Honda Element and this video was very informative. Months ago I was in a heavy rain downpour and my check engine light came on with a P0420 code. I cleared it but now it came back again. My car has over 218,000 miles. I bought new sensors anyway and plan to install them but taking it to my mechanic to install and check the system anyway. The car runs good and I have added Cataclean to see if that helps. Short term bank 1 fuel trim 6.2%. Long term bank 1 fuel trim 3.9%.
Just went through a headache of a time on my 2010 wrx. Most places sold me the wrong air fuel sensor. Finally researched I needed the wideband sensor. Every one except autozone tryed selling me the narrowband sensor. Denso 234-9108 is correct one for WRX.
excellent video on this topic. I had a "lean bank 1" code for my Ford Taurus and one of the problems I had was a valve cover gasket leaking oil on to the exhaust manifold creating quite a bit of oil smoke! the location of the leak was right next to the O2 sensor! I had rough idling, bucking especially when cold, the check light problem, and you're the 1st person that has indicated that oil contamination (though you didn't mention "smoke" related to burning oil on the hot surface of the exhaust manifold as a possible cause) could cause a problem with the sensor, especially the part open to the atmosphere. to my knowledge, there was no oil directly ON the wire going into the sensor, but of interest once I cleaned the wire area going into the sensor with a shop towel wet with 91% isopropyl alcohol, things cleared up. it's been running great since I did that. If the sensor was "bad" most likely this superficial cleaning would not have fixed that. I'll keep my fingers crossed!
I would enjoy a followup regarding O2 sensor heater control circuit high/low codes (P0031 & P0032). This will also cause an open loop condition in some Subarus. I'm pretty sure the ECM sends a PWM signal to the heater, switching the ground, and if it isn't detecting proper resistance?? from the heater, it will shut off the O2 sensing, defaulting to open loop (14.7 fuel/air ratio).. Of course, a bad heater or heater wiring will cause this. There's something else causing this in my 04 Baja. Really pissing me off. I'm sure a lot of folks are chasing this error. Any help would be great.
My 03 Bean, which I've had since new, threw an oxygen sensor code about three years ago. It's always been garaged and has never had an engine fault. My mechanic replaced the sensor (although he said it was a real pain to get out) and all was fine, but I had him go ahead and replace the other two sensors. After that the engine seemed to run much, much smoother. I guess 15 years is about the life span of these sensors before they start deteriorating. BTW, my wife's 02 Camry (also since new) threw a front oxygen sensor code a few years ago. I got an OEM Denso sensor for less than $100 from Amazon and it took 15 minutes to replace it as it's on the top front of the engine. Couldn't have been easier.
cheers, well as ive had no replacements in any gaskets no failures and the ol FB25 is doing well at 200k klm it seems like its a sensor failure burnout with age.
Superb underrated video. This deserves way more views. MrSubaru, I am almost finished swapping a jdm ej20x long block on my ‘05 OBXT. Everything above the long block remained USDM. But I noticed these jdm engines have the main O2 sensor at the beginning section of the Down Pipe, rather than on the Up pipe. I disabled the exhaust AVCS since I’m using the usdm ECU. Being the main O2 sensor is on the Down Pipe for the ej20x motor, do you think this might influence the correct operation of the car?
awh......you did that one just for me.....JK........great video and great explanation on operation and failure causes. Keep the Subie information coming.....I like where this is headed with sensors stuff in future videos.
I just so happen to have a check engine code for O2 sensor that began shortly before my radiator sprung a leak and another code was present for either thermostat or fan malfunction , the fan is operating so it's the thermostat. I believe the faulty thermostat likely caused the old radiator to become pressurized and rupture. 2002 Subaru Forester S with 148k miles. Not sure exactly how any of the coolant problems may have affected my O2 sensors but i have no head gasket leakage that's detectable yet.
Watching this now appreciate your videos I've changed and fixed a few things Watching your channel 😊thank you I can not get OEM oxygen sensor for 93 subaru what manufacturer are you recommending currently..I say currently because the video is from a couple yrs ago 😊😊😊 And.... back to watching ❤
I have a question or 3. First let me say thank you for your time and effort in making these instructional videos. I've found them very useful. I have a 2002 Outback sedan with the ej25. I bought it 2yrs ago with 163K on it and it came with Blue FelPro MLS headgaskets. I have 193K on it now. I bought the OE new gaskets that are the 642s the latest rendition from what I've found. I'm wondering do you think if be better off getting a new low mileage engine from JDM for like $1,500 or rebuild it myself? I've built an engine before gm 350 small block. But I'm sure it would cost me the same if not more. I've also read that some of the connections are different on the ones from Japan but I assume I can just swap those from mine. I've already replaced all 4 wheel bearings, bushings, struts, drilled and slotted rotors with ceramic pads and new tires. I love this car and even used cars are stupid priced and can't touch a good used car for what I'd spend to fix this one. The interior and exterior is in really good shape. I had an Aisin timing belt and water pump kit coming from Amazon but then they canceled the order stating it didn't meet quality specs which I found odd. Any advice or direction you can point me is HUGE and greatly appreciated. Thanks in advance.
Thanks so much for this explanation of the O2 sensors. I have a 2012 Outback 2.5i manual with recurring check engine light related to the 02 sensors... or is it something else? Multiple Subaru dealerships tell me they don't repair/replace only the sensors, but have to replace almost the whole exhaust system (manifolds, sensors, catalytic converter, etc.), for about 4000 $!!! What should I do? Can I drive the car without causing too much problems (carbon buildup and what else) ? Thanks.
Yooo...my respects to you brother....yea I have a 2006 subaru outback...simple not turbo...only 140 k miles..anywho...p0303 and well alot more..the fan the evap...the everything is sending codes...I was dumb .I put gas in from a dirty can :( on the farm 🚜 gotta be careful where u get ur fuel from.
Are you spying on me? Lol I'm on a whatsapp group and someone was asking about O2 sensor so I was trying to explain... Great timing. All the best from Chile.
Haha 3rd comment lol This was an excellent video When the time comes which might be now ... i see it has a check up on car with the descriptions given with different issues color and visual. What would normal look like 200000 miles
Great video! My Legacy wagon 2006 EJ204 has a P0130 code. Bank 1 Sensor 1. I replaced the sensor in front of the catalytic converter but nothing has changed. Do you know if it can be the sensor after the catalytic converter or what else can be the problem?
Hi! Thank u for your videos! Can u tell me please from were to start searching: Gda wrx slight pulsaiting while slow acceleration or cruising, if wot car flys very well. New sparks new coils etc. Car is bone stock, no leaks, I know the car quit well, so such things as sparks,leaks etc, i have I excluded. Can such slight pulsating,Hesitaiting caused by low fuel pressure or o2 sensor? Thanks!
I just drove cross country and halfway through Kansas I heard a loud sputtering sound. It was like a train. I pulled over and dad helped me figure out it was the oxygen sensor that was rattling and let loose. The updraft. We had to buy one and replace it to keep trekking. It was mostly an easy fix but the fact that the shop I took it to prior to the trip didn’t catch how loose it was, is just disheartening. They also didn’t even check the spark plugs or change oil filter or the melted-on gaskets on the transmission oil head. So many other issues. I have an ‘07 forester with 85,000 miles. Oh goodness the brakes were incredibly crusted on. Not even wheeling them helped. We just replaced the entire shoe and we’re able to salvage the discs and clean them up. Long story short the car came from Massachusetts and had never been officially serviced since. So I’m slowly getting up to speed. I have images I’d really love to email you if you ever want to share with your audience! Best regards.
I hate to say it, but I wouldn’t trust any shop or dealership on a Full Multi Point inspection… when I owned a brand new 09 Chevy, I paid a little extra for the lifetime oil which included an “inspection” of ; Brakes, Tires, Lights, Filters, etc. Well I had something go out or “bad” no less than 150 miles after my last oil change, and I said to the dealer; I thought y’all checked this along with all these things at every oil change? They said it’s more so a Visual Inspection, as in, if they see it and it noticeably needs replacing/repaired, then they do but that they don’t physically/literally put hands on each specific thing… which means they go down the 44 point check list and just cross them all out after doing a oil change and call it good. Granted this is a little different than say taking a rig in for a $200+ inspection and service, but again, I bet you anything a lot of it is briefly glanced at, doesn’t even have hands put on it….
Very informative, I may replace the sensors in my daughter’s ‘09 Impreza NA as a precaution. 106k miles, gas mileage isn’t great, like 22. No codes. It does use some oil so will be interested to see what they look like. One suggestion: tell us what brand of sensors you recommend. Thanks.
Hi everyone and mr.subaru my impreza blobeye 2.0 gx 2003 125hp 92kw wagon has a problem with starting up. It always starts but its weird. Summer times its cranking up like 5-10seconds. Winter time on cold start it starts immediatly. If i turn the car off and start it in a minute it starts immediatly, but if i leave it for like 15mins+ it crancking like 10seconds. As i know car is doing that for like 10years i bough it like that. It has 230000km and original engine. Do you maybe have a video on that or any clue what could it be. I have zero engine codes? Love your videos 😃
My 1997 Rodeo 2.6 4 cyl infrequently gives code for EGR insufficient flow. I've cleaned the valve and manifold...even replaced EGR twice...but still get occasional code. Can the 02 sensor be involved? This vehicle does not have sensors to measure flow thru EGR.
Symptoms?? First start cold start.. idling issues need to keep idling at 1100 to 1500 till almost to temperature then all is well. If i don't warm up enough before leaving it might stall at red light/ stop sign... possibilities of related to oxygen sensor and or idle air control valve
Could an alternator failure possibly cause and old oxygen sensor to intermittently cause the check engine light to go on and off after the alternator is replaced? EJ251 with 144K miles. Long story behind the alternator failure and why the sensor code wasn't fully investigated but currently, after about 700 miles, the light is out.
I have a 2016 Forester with 110K miles. Periodically get the P0171 code, RIGHT at startup, never as I’m driving. I did have a local shop check it and they claimed it was a stored code and fuel trims were where they should be, but after a reset, two weeks later the same code popped up again at startup. I have changed PCV and hose, cleaned throttle body and MAF, without change except smoother idling. Plugs have never been done( I know, it’s on the list). O2 sensor never changed . What’s your take on this? Any help is appreciated, thanks!
Considering replacing my stock y pipe on a 94 legacy L 2.2 with a header, looks like I will have to weld a bung in for sensor upstream, also, I have a new catalytic I could install, as I want to go ahead and just put all new exhaust on it. If I mimic the positioning of the stock O2 sensors and keep the stock muffler do you think that will work with the ecu?
I had a bad gasket after the Y pipe this year and replaced it, but mileage seemed to suffer after the gasket replacement, didn't change anything else, seems to run very rich on start up. It is also very cold now.
So just bought a 2010 sti hatch , has 122000 miles on body, just pulled intercooler off and saw I have a iag stage 2 tough block installed at 80000, has a downpipe and exhaust , it smells rich at idle and it has black in the exhaust tips. No oil leaks or coolant leaks no vacuum leaks . I’m thinking when he blew the original motor in the car it had oil/ coolant go through the exhaust , and I’m hoping they just didn’t replace them, just spent 300$ on new sensors….. I’ve tried everything I can think of just hope it works …. Any advice. It’s stage 2 tune also
excellent video congratulations, I have a question. What happens to the oxygen sensor when a car is put direct pipe? completely removed? does it seriously affect performance?
Mr. Subaru I see you are in SC near Charlotte, I'm in Fayetteville, NC with 3 Subies 2 WRXs 2005 Sportwagon w/STi mods 2021 base WRX and a 2021 Crosstrek w/manual trans. Have you found a reliable source for the black Japanese oil filters for the WRX? Thank you
This was probably the best explanation of O2 sensors I have seen. Simple, easy, informative and practical all at once. Wish we had this at Automotive Tech school many years ago.
What do you think?
I just want to say thank you for your videos i have learned so much. I am a grandma who's 03 Outback was my grand youngins school bus. But it quit running. So i really love your content, you've given me, a super non mechanical granny the confidence to crawl under my car and try to do some trouble shooting myself. I appreciate what you do & thanks again.
It's been a long time since watching Mr Subaru. Happy to see any Subie fix vid where he talks nerdy and explains fundamentals beyond just showing things wrenched. More how to vids please.
yes, understanding the scenarios that the AF or O2 sensors get involved in, helps a lot with understanding error code diagnostics & source-of-the-problem finding.
You can’t get any better information than Mr. Subaru.
Please do a similar video regarding Cats and P0420 diagnosis and repair. Thanks!
I was not expecting to learn anywhere near this much from this video as I did. Excellent information and very well laid out. 👍🏼
Wow ! This was the best explanation of O2 sensors i had in my life...I have a Subaru Legacy 2013 with only 67.000 Klm and i really enjoy your work thk's.
Thanks for the great intro to oxygen sensors!
I had one of the older Subaru Outbacks you speak of. An 01’. When I bought it the head gaskets were blown unbeknownst to me. My father in law and I redid the engine and it ran nice for a long time. I live in NY so eventually the rust got to it, put a crack in the actual fuel tank. The o2 sensors did their job -never threw a code.
Very informational and well laid out video. I can’t wait for what you have next!
Excellent review, it should be noted that heat is the lowest form of energy. Just about everything generates heat as a byproduct. The O2 sensor takes heat and turns it to electricity, a higher form of energy. That's why they wear out. FYI.
Great stuff! But you MUST now do the follow up on Wideband sensors which wld be pre-cat sensor in almost all Subies since early-mid 2000s ... very important to understand failure modes and can be tricky😱 After a long diag, finally discovered an intermittent failing wideband O2 with a P0030 code on 2004 Forester with EJ251 was caused by sensor element internal resistance not falling quick enuf to meet PCM programmed parameters ... in this case, PCM requires less than 50ohms within 30sec of start or after fuel cut off condition. Very tricky to nail this, but wen u r going to charge a customer $700 for a new part that u can’t return u need to be dead certain. Lets do failure modes, diag and test procedures on wide bands? 😉👍
Coolant takes them out too,the Fords with the 3.8 which had headgasket problems would take them out when the headgaskets blew. ln certain year Dodge truck,the O2 sensor also is involved with shifting of the transmission.Have fixed a few transmission problems in these replacing the rear O2 sensor.Do not top off the gas tank,EVAP system needs space and have seen O2 sensor codes appear from this
Wow this was awesome. The best explanation of something that I have been puzzled about it. Thank you Sir,
I'm working on figuring out the cause of my catalyst efficiency codes so this was great timing.
I've long determined the converter is gone, but working on debating if I should swap the sensors "while I'm in there"
A plethora of much needed answers and then some, GREAT VIDEO! THANKS!
Best O2 sensor explanation on UA-cam, very clear and detailed explanation. Thanks sir!
Great Video as always. Picked up a used 2015 Crosstrek Premium with 92K mile for my kid. I've been doing various things and this is one I like to do at 90 -100K. Relative to the other Subaru's O2 sensors it's in a pretty easy spot to get to. Replaced the front one with a Denso brand which seemed to be the exact same as the OEM I removed. Right down to the color of the wire coating and wire tie fastener. I consider it inexpensive insurance for the future.
Top 20 comments, SWEET!
Mr.Subaru you’re VERY HELPFUL
I watch your videos for fun and information
Great explanation. There is a lot of bad information out there on the internet about these sensors that I found when troubleshooting a P0420 code on my '10 OB specifically the many folks saying to replace both O2 sensors. Mine were working correctly and the downstream sensor was telling me that something was wrong thus setting the P0420 code for catalyst insufficiency. I cured that with three treatments of Cataclean and no recurrence some 1000 miles later (I suspect that I disturbed a bunch of crap in the vapor collector when I overfilled the gas tank and temporarily shot crap through the engine). Keep these videos coming - they're great.
Advanced chemistry and it was explained in mr subaru terms. Good knowledge to really understand O2 sensors
I remember giving my tuned rs to a shop in Utah that “specialized” in Subarus to fix a surging issue I had while driving, left it at their shop for three months while I was out of the country and came back to them “solving” it by replacing my charcoal canister. I took it to Colorado for a friend’s bucking and surging the whole way there, under wot it ran normally. I happened upon the Subie Doctor while in Colorado and within ten minutes of looking at it had already diagnosed the issue and put in a brand new oem o2 sensor.
Very well explained. I've seen more air/fuel sensor problems than O2 sensors with Subaru.
We are purchasing our first Subaru after 50 years of driving. I hope I don’t regret the direct injection and it turns out to be a good vehicle
WOW - a super solid video! Learned alot - especially to not use dielectric grease at the fitting/ might block fresh O2. Excellent.
Excellent pace and clear explanations. Like some before me, I agree this is so far the best explanation of O2 sensor function and diagnostic. 👍
This was an amazing video!! Love that you mentioned the h6, it's so hard to find information about this motor on I think because they're just so solid.
Great presentation. I have a 98 honda Accord that has several O2 sensors die. It also burns one quart of oil per 1000 miles. You are the first to associate oilcontamination. Thanks.
This is top quality content right there!
I am really loving these in depth component explanation videos.
Thanks, Robert!
As a chemical engineer who works with these sorts of things, I give you an A+. Excellent job. Thank you for correctly pronouncing stoichiometric. I have heard some folks just slaughter the word. You obviously had to prep for this one. Looking forward to the next video. Thanks. 🏳️🌈
Finally, a most comprehensive explanation on this item. Question though : will the slots in the casing determine the workings.? My supplier insist that the one with the smaller slots are the correct based on the part number. But after installing, engine kinda running weird - like a very short hesitation when acceleration.. Especially when the AC is on..
Thanks for the great video..👍
very informative… thanks you for your explanation how the o2 sensors work…✌️
Extremely helpful info. I’m having an issue right now where my new O2 sensor just doesn’t work suddenly and this gives me a lot to look for when I remove it from the manifold/uppipe.
Talk about perfect timing, I had my 2010 Forester serviced last month for (System too lean {Bank 1}), and the A/F sensor was replaced. A week later the Check Engine came back on with the same code via (Hum by Verizon P017) which turned out to be more than the sensor itself. Intake Manifold Gasket/Fuel Pump/InjectorSeals/PCV Valve. Not bad for a high mileage vehicle 412,433+.
I will be doing a complete front-end overhaul by April 2022. In 2023/24 my goal is to buy a new Forester when I retire and hold onto this ole girl...
Thank you for this O2 explanation!! Great detail and easy to understand!!
Informative, authoritative, well illustrated. I watched several videos on O2 sensors and this one was the best.
Good stuff. Dealing with a lean condition. This helps tons.
Thanks for all the info.
Don’t have a Subaru but have an 04 Honda Element and this video was very informative. Months ago I was in a heavy rain downpour and my check engine light came on with a P0420 code. I cleared it but now it came back again. My car has over 218,000 miles. I bought new sensors anyway and plan to install them but taking it to my mechanic to install and check the system anyway. The car runs good and I have added Cataclean to see if that helps. Short term bank 1 fuel trim 6.2%. Long term bank 1 fuel trim 3.9%.
Just went through a headache of a time on my 2010 wrx. Most places sold me the wrong air fuel sensor. Finally researched I needed the wideband sensor. Every one except autozone tryed selling me the narrowband sensor. Denso 234-9108 is correct one for WRX.
Interesting as always! Good presentation.
Side note: a faulty downstream o2 can cause high or erratic idle with no check engine code. On an ej251
Very good video and great info to boot, cant wait for more to come
Thank you 🙏 my man you did very good explanation.You make the world 🌎 a better place 🥰🇺🇸💯👀
As usual great stuff !
Thank you sir. May I have another great educational video 👍🏼
Superb video and explanation - many thanks for sharing 👍
Great video, very informative!
Very informative many thanks
What a great video. Thank you for going in to depth.
This is a very well explained video brother 👌🏽
excellent video on this topic. I had a "lean bank 1" code for my Ford Taurus and one of the problems I had was a valve cover gasket leaking oil on to the exhaust manifold creating quite a bit of oil smoke! the location of the leak was right next to the O2 sensor! I had rough idling, bucking especially when cold, the check light problem, and you're the 1st person that has indicated that oil contamination (though you didn't mention "smoke" related to burning oil on the hot surface of the exhaust manifold as a possible cause) could cause a problem with the sensor, especially the part open to the atmosphere. to my knowledge, there was no oil directly ON the wire going into the sensor, but of interest once I cleaned the wire area going into the sensor with a shop towel wet with 91% isopropyl alcohol, things cleared up. it's been running great since I did that. If the sensor was "bad" most likely this superficial cleaning would not have fixed that. I'll keep my fingers crossed!
Great presentation, well worth the time
As always, great work! Just think when you started you didn't want to talk! LOL
I would enjoy a followup regarding O2 sensor heater control circuit high/low codes (P0031 & P0032). This will also cause an open loop condition in some Subarus. I'm pretty sure the ECM sends a PWM signal to the heater, switching the ground, and if it isn't detecting proper resistance?? from the heater, it will shut off the O2 sensing, defaulting to open loop (14.7 fuel/air ratio).. Of course, a bad heater or heater wiring will cause this. There's something else causing this in my 04 Baja. Really pissing me off. I'm sure a lot of folks are chasing this error. Any help would be great.
Same here I've changed sensors twice and still have the problem
Very well done...
My 03 Bean, which I've had since new, threw an oxygen sensor code about three years ago. It's always been garaged and has never had an engine fault. My mechanic replaced the sensor (although he said it was a real pain to get out) and all was fine, but I had him go ahead and replace the other two sensors. After that the engine seemed to run much, much smoother. I guess 15 years is about the life span of these sensors before they start deteriorating.
BTW, my wife's 02 Camry (also since new) threw a front oxygen sensor code a few years ago. I got an OEM Denso sensor for less than $100 from Amazon and it took 15 minutes to replace it as it's on the top front of the engine. Couldn't have been easier.
My 09 outback needed a new O2 sensor to pass inspection last summer. A $350 repair.
Thank you for this explanation!
cheers, well as ive had no replacements in any gaskets no failures and the ol FB25 is doing well at 200k klm it seems like its a sensor failure burnout with age.
Thank you I appreciate it it's very very helpful I appreciate great and blessed
You're not long winded. It's fine. I want to learn. :)
Great video well done sir 👏
Superb underrated video. This deserves way more views. MrSubaru, I am almost finished swapping a jdm ej20x long block on my ‘05 OBXT. Everything above the long block remained USDM. But I noticed these jdm engines have the main O2 sensor at the beginning section of the Down Pipe, rather than on the Up pipe. I disabled the exhaust AVCS since I’m using the usdm ECU. Being the main O2 sensor is on the Down Pipe for the ej20x motor, do you think this might influence the correct operation of the car?
awh......you did that one just for me.....JK........great video and great explanation on operation and failure causes. Keep the Subie information coming.....I like where this is headed with sensors stuff in future videos.
I just so happen to have a check engine code for O2 sensor that began shortly before my radiator sprung a leak and another code was present for either thermostat or fan malfunction , the fan is operating so it's the thermostat.
I believe the faulty thermostat likely caused the old radiator to become pressurized and rupture.
2002 Subaru Forester S with 148k miles.
Not sure exactly how any of the coolant problems may have affected my O2 sensors but i have no head gasket leakage that's detectable yet.
Question: As a sensor degrades with age does it tend toward a rich or lean running engine?
Excellent video.
Very helpful!
Thanks,!
Watching this now appreciate your videos I've changed and fixed a few things Watching your channel 😊thank you
I can not get OEM oxygen sensor for 93 subaru what manufacturer are you recommending currently..I say currently because the video is from a couple yrs ago 😊😊😊
And.... back to watching ❤
Good work air
Great video!
I have a question or 3. First let me say thank you for your time and effort in making these instructional videos. I've found them very useful.
I have a 2002 Outback sedan with the ej25. I bought it 2yrs ago with 163K on it and it came with Blue FelPro MLS headgaskets. I have 193K on it now. I bought the OE new gaskets that are the 642s the latest rendition from what I've found. I'm wondering do you think if be better off getting a new low mileage engine from JDM for like $1,500 or rebuild it myself? I've built an engine before gm 350 small block. But I'm sure it would cost me the same if not more. I've also read that some of the connections are different on the ones from Japan but I assume I can just swap those from mine. I've already replaced all 4 wheel bearings, bushings, struts, drilled and slotted rotors with ceramic pads and new tires. I love this car and even used cars are stupid priced and can't touch a good used car for what I'd spend to fix this one. The interior and exterior is in really good shape. I had an Aisin timing belt and water pump kit coming from Amazon but then they canceled the order stating it didn't meet quality specs which I found odd. Any advice or direction you can point me is HUGE and greatly appreciated. Thanks in advance.
Thanks so much for this explanation of the O2 sensors. I have a 2012 Outback 2.5i manual with recurring check engine light related to the 02 sensors... or is it something else? Multiple Subaru dealerships tell me they don't repair/replace only the sensors, but have to replace almost the whole exhaust system (manifolds, sensors, catalytic converter, etc.), for about 4000 $!!! What should I do? Can I drive the car without causing too much problems (carbon buildup and what else) ? Thanks.
Yooo...my respects to you brother....yea I have a 2006 subaru outback...simple not turbo...only 140 k miles..anywho...p0303 and well alot more..the fan the evap...the everything is sending codes...I was dumb
.I put gas in from a dirty can :( on the farm 🚜 gotta be careful where u get ur fuel from.
Got a new fuel pump nd filter
..but I'm thinking bits the distributor...ughhh..I just...anyway good riddance 🤪
Well done mate
Are you spying on me? Lol I'm on a whatsapp group and someone was asking about O2 sensor so I was trying to explain... Great timing. All the best from Chile.
Haha 3rd comment lol
This was an excellent video
When the time comes which might be now ... i see it has a check up on car with the descriptions given with different issues color and visual. What would normal look like 200000 miles
I wonder if Subaru is starting to use the air fuel sensors behind the cat to do more things with, I've noticed late model Toyotas have.....
Great video! My Legacy wagon 2006 EJ204 has a P0130 code. Bank 1 Sensor 1. I replaced the sensor in front of the catalytic converter but nothing has changed. Do you know if it can be the sensor after the catalytic converter or what else can be the problem?
I need to send this video to my local Subaru dealer, I knew and fixed my Legacy, the dealer couldn't. ...it's called diognosing....lol
Hi! Thank u for your videos!
Can u tell me please from were to start searching:
Gda wrx
slight pulsaiting while slow acceleration or cruising, if wot car flys very well.
New sparks new coils etc.
Car is bone stock, no leaks,
I know the car quit well, so such things as sparks,leaks etc, i have I excluded.
Can such slight pulsating,Hesitaiting caused by low fuel pressure or o2 sensor?
Thanks!
thanks a very ggod explanation.
I just drove cross country and halfway through Kansas I heard a loud sputtering sound. It was like a train. I pulled over and dad helped me figure out it was the oxygen sensor that was rattling and let loose. The updraft. We had to buy one and replace it to keep trekking. It was mostly an easy fix but the fact that the shop I took it to prior to the trip didn’t catch how loose it was, is just disheartening. They also didn’t even check the spark plugs or change oil filter or the melted-on gaskets on the transmission oil head. So many other issues. I have an ‘07 forester with 85,000 miles. Oh goodness the brakes were incredibly crusted on. Not even wheeling them helped. We just replaced the entire shoe and we’re able to salvage the discs and clean them up. Long story short the car came from Massachusetts and had never been officially serviced since. So I’m slowly getting up to speed. I have images I’d really love to email you if you ever want to share with your audience! Best regards.
I hate to say it, but I wouldn’t trust any shop or dealership on a Full Multi Point inspection… when I owned a brand new 09 Chevy, I paid a little extra for the lifetime oil which included an “inspection” of ; Brakes, Tires, Lights, Filters, etc. Well I had something go out or “bad” no less than 150 miles after my last oil change, and I said to the dealer; I thought y’all checked this along with all these things at every oil change? They said it’s more so a Visual Inspection, as in, if they see it and it noticeably needs replacing/repaired, then they do but that they don’t physically/literally put hands on each specific thing… which means they go down the 44 point check list and just cross them all out after doing a oil change and call it good. Granted this is a little different than say taking a rig in for a $200+ inspection and service, but again, I bet you anything a lot of it is briefly glanced at, doesn’t even have hands put on it….
Very informative, I may replace the sensors in my daughter’s ‘09 Impreza NA as a precaution. 106k miles, gas mileage isn’t great, like 22. No codes. It does use some oil so will be interested to see what they look like. One suggestion: tell us what brand of sensors you recommend. Thanks.
Great job thank you I appreciate it
I just replaced the downstream O2 sensor in my 2002 Forester this morning.
Was it kicking a check engine light?
Bad a*% young man!
Thank you for the information
Hi everyone and mr.subaru my impreza blobeye 2.0 gx 2003 125hp 92kw wagon has a problem with starting up. It always starts but its weird. Summer times its cranking up like 5-10seconds. Winter time on cold start it starts immediatly. If i turn the car off and start it in a minute it starts immediatly, but if i leave it for like 15mins+ it crancking like 10seconds. As i know car is doing that for like 10years i bough it like that. It has 230000km and original engine. Do you maybe have a video on that or any clue what could it be. I have zero engine codes? Love your videos 😃
Question, does Subaru still weld a hex bun, that the sensor screws in. If so is it still 24mm size.
My 1997 Rodeo 2.6 4 cyl infrequently gives code for EGR insufficient flow. I've cleaned the valve and manifold...even replaced EGR twice...but still get occasional code. Can the 02 sensor be involved? This vehicle does not have sensors to measure flow thru EGR.
Symptoms??
First start cold start.. idling issues need to keep idling at 1100 to 1500 till almost to temperature then all is well. If i don't warm up enough before leaving it might stall at red light/ stop sign... possibilities of related to oxygen sensor and or idle air control valve
I literally just changed both of mine on my 2004 wrx. Now I have a P0171 which is caused by my engine airbox, lost 3 of 4 box clips.
Clean your mass air flow sensor
Could an alternator failure possibly cause and old oxygen sensor to intermittently cause the check engine light to go on and off after the alternator is replaced? EJ251 with 144K miles. Long story behind the alternator failure and why the sensor code wasn't fully investigated but currently, after about 700 miles, the light is out.
I have a 2016 Forester with 110K miles. Periodically get the P0171 code, RIGHT at startup, never as I’m driving. I did have a local shop check it and they claimed it was a stored code and fuel trims were where they should be, but after a reset, two weeks later the same code popped up again at startup. I have changed PCV and hose, cleaned throttle body and MAF, without change except smoother idling. Plugs have never been done( I know, it’s on the list). O2 sensor never changed . What’s your take on this? Any help is appreciated, thanks!
Considering replacing my stock y pipe on a 94 legacy L 2.2 with a header, looks like I will have to weld a bung in for sensor upstream, also, I have a new catalytic I could install, as I want to go ahead and just put all new exhaust on it. If I mimic the positioning of the stock O2 sensors and keep the stock muffler do you think that will work with the ecu?
I had a bad gasket after the Y pipe this year and replaced it, but mileage seemed to suffer after the gasket replacement, didn't change anything else, seems to run very rich on start up. It is also very cold now.
So just bought a 2010 sti hatch , has 122000 miles on body, just pulled intercooler off and saw I have a iag stage 2 tough block installed at 80000, has a downpipe and exhaust , it smells rich at idle and it has black in the exhaust tips. No oil leaks or coolant leaks no vacuum leaks . I’m thinking when he blew the original motor in the car it had oil/ coolant go through the exhaust , and I’m hoping they just didn’t replace them, just spent 300$ on new sensors….. I’ve tried everything I can think of just hope it works …. Any advice. It’s stage 2 tune also
I have over 200,000 miles (EJ253), should I have new sensors to spare?
Would you change the cat converter if you're changing the sensors?
excellent video congratulations, I have a question.
What happens to the oxygen sensor when a car is put direct pipe?
completely removed?
does it seriously affect performance?
Direct pipe?
@@MrSubaru1387 Straight Pipe Exhaust System
sorry but i use google translate
If you remove the catalytic converter, no, doesn't affect performance. Just illegally removes a pollution control.
@@MrSubaru1387 thanks for the explanation and great channel
Mr. Subaru I see you are in SC near Charlotte, I'm in Fayetteville, NC with 3 Subies 2 WRXs 2005 Sportwagon w/STi mods 2021 base WRX and a 2021 Crosstrek w/manual trans. Have you found a reliable source for the black Japanese oil filters for the WRX? Thank you
I buy my Japanese filters directly from Japan. Japanparts.com