How I Diagnosed My Failed Oxygen (Air Fuel Ratio) Sensor - BMW DIY

In this video I show you how I was able to diagnose my bad O2 sensor . I have a 2008 BMW 335i with the N54 twin turbo inline 6 cylinder engine. It turned out to be bank 2 sensor 1 that was bad. I had a number of random misfire codes and mixture codes but nothing specifically pointing to a bad oxygen sensor.
If you think you might have a bad sensor but aren't sure what signs to look out for before the sensor completely fails this video should be helpful.
If you have a BMW 335i and need a sensor you can buy one here (it helps the channel):
Bank 1 Upstream:
bit.ly/2WXaD9l
Bank 2 Upstream:
bit.ly/2ticRCG
Bank 1 Downstream:
bit.ly/2UP6r9T
Bank 2 Downstream:
bit.ly/2tdIi12
If you have a BMW and want to setup the software shown on my laptop:
We are using the INPA software suite to code the injectors.
Link to a thread showing how to setup INPA/NCS Expert:
www.e90post.com/forums/showthr...
If you have Windows 10 64-Bit:
www.e90post.com/forums/showthr...
You can find the INPA cable online at places such as Amazon or Ebay. Search INPA Cable K+D Can. When you see the word "affiliate" listed beside any link in my description please know that this is a custom link and I will earn a small commission if you opt to purchase using said link. This is at no extra cost to you so it's a win all around :) Thank you!

[@davidgarry2687]

Hands down the best DIY n54 videos on KZbin! Extremely detailed and well explained. Thank you so much for the education!!

[@stonesthrow420]

My 2003 X5 has the 3 litre M54 engine, and this completely explains what is going on with my rough idle.....new plugs, new coils, new MAF, new gaskets...etc. No vacuum leaks. After a good quick drive on the freeway, engine is good and warmed up, runs like a new vehicle...goes into closed loop at idle, runs like garbage with misfire codes and fuel trim codes. Im gonna change out bank two O2 sensor immediately! Thanks for the great video...it helps people understand how o2 sensors work, and the purpose of closed loop on a modern fuel injection system. BRAVO

[@semperer]

Thank you for the video I just found out that owner before put Diesel lambda sensors into the 335i N54..... thats crazy... and this crap from exhaust proved that my car is running rich

[@micraw714]

You always seem to post videos at the appropriate time when I'm having the exact same issues with mine brother 😁

[@Mercury_EG]

truth

[@victorc1611]

I second that.

[@alcetus3]

I just fixed my misfires and limp mode because of this video. thank you for this awesome informative video. When first startup, running real rich, clear codes and ran fine until i got into the power band at WOT. then got o2 sensor errors, and misfires. Love your videos. (2008 335i, 112,000 miles. FBO except still running stock intercooler, MHD BEF, JB4 piggy back tune map 2 mostly)

[@fasnaeem6678]

As always keep up the great and informative videos making owning my N54 a lot less stressful and daunting and encouraging me more and more to work on it myself!

[@friguy4444]

You.....ROCK!!!!! LOL. I can't tell you how much you've helped me with this video. Thank you so much. It seems like no one talks about the importance and or effects the O2 sensors have on our cars. I have an E46 M3 and I just changed out my OEM Catted Headers for a set of catless ones and I have had a real problem with the car having codes on the O2 sensors as well as many other codes just coming up even after I've done a tune that is supposed to adjust the sensors for that particular set up. Miss fire codes and strange stuff. Exactly what you have described and shown here. You were so thorough and I am so glad. I am having the miss fire codes just like you had on bank 2 but only on bank 1 cylinders. (Cylinders 1&2) indicating it is likely the O2 sensor on that bank (as you similarly showed) that is the culprit. It has shown a couple of times where both pre cat sensors are throwing codes. But usually it's only showing a code for the pre cat sensor on only bank 1. I have been thinking that it could be so many things that I just wasn't sure enough yet to pop for any one or two parts to try and solve it. I thought maybe vacuum or ground problems. But I'm sure enough now to start with this. Thank you again!

[@LuanNguyen-rm3pb]

Thank you so much for your tutorial video. It's really excellent. I bought a 2013 BMW 328i xDrive N20 4 Cyl in Dec 2019. It had drivetrain malfunction and misfire on Cyl 2. The dealer suggested to replace 4 coils & spark plugs. I replaced the 4 coils and 4 spark plugs, and the battery (was low). The drivetrain mal function error went away, but the misfire error persisted. I replaced the fuel injector (looked black) on Cyl 2 to no avail. Yesterday, I cleaned the MAF (look new and clean to begin) to no avail. Your video suggested my car may have O2 sensor issue. I will give it a run and checked the 4 spark plugs as you did to confirm the black sud on #2; I may have more than 1 Cyl misfire. I think my car may not have bank 1 and 2 as your N54. Much thanks to any suggestions you may have. Thanks again. This video is really excellent.

[@DRNLR]

Thanks for the detailed info on how to change the spark plugs. The steering rack removal was the key to this DIY. I bought the exact socket from FCP euro and it made the spark plugs much easier to deal with.

I have a Mercedes W203 that was smoking a lot. I had no idea what to do. Thanks man. You saved my life (and my pocket).

[@HumbertoBenavidesphotographer]

As always, very nice info and videos from you !

[@Itisinthehand]

Have 630i n53, but there was loads of good stuff here to help me tackle mine.Thanks for uploading. Great.

[@Ashdowne9]

DANG!!! This was EXACTLY what I needed. Wow. Thank you SO much for this fantastic descriptive video. Now I know exactly what my problem is. I'm very excited to fix it now! Thank you !!!

[@samuelwilliams7331]

Love the education you give out. This is on my todo list.

[@Mercury_EG]

Really happy I stumbled across this, I grabbed up a used BMW and it has the rough idle, as soon as I figured out it was about 30 seconds to a minute I instantly though heater, but since I am not familiar with BMW I figured it couldnt be that simple right? Well I will run this test in the am, and am doing a full drain and replacing everything anyways, just add the o2 sensor to the list

[@danteruiz4356]

uuu god i love you man... like the best teacher ever, i have exactly the same problem, but not the same tools :( ... but now i know what to do thanks to you... greetings from Chile!!!!

[@zoober2217]

I follow and another N54 content channels, but this channel is different! This is better! Absolutely useful DIY's!

[@pochron1105]

Worth adding that on a cold engine [O2 sensor not heated up] and during hard acceleration[O2 sensor too slow for what you try to do], it's the mass airflow sensor that takes over, so that lambda values can be estimated/guesstimated from the lookup data.

[@SL9SH]

There are no crap MAFs on an N54, just MAP

[@nickolascain2994]

informative as always! Thanks for the helpful info.

[@stephanelouvet1113]

Awesome troubleshooting help ! Thank you !

[@louiecabadas812]

Good video and accurate information. Don’t stop making these types of videos bro

[@matthewweisdorfer7757]

I have replaced all of my o2 sensors on my N54. The pre-cats I did at 120k proactively. The post cats, I got a specific code. The post cats really don’t do much other than monitor the pre-cats and make sure they are running correctly. You can also monitor them live on a scanner. The scanner should have specific values. If values aren’t what they should be, then you know what specific O2 sensor is bad. Easiest thing to do is take the cats out of the car if you are looking to change them out. They are a PITA otherwise.

[@libotean28]

Damn, i thought it would be an expensive 2021 but you just saved me hella money since BMW said it was my Injectors! Thanks a lot for the video and for sharing your knowledge.

[@raiderwraps8317]

Same here bro im like huh hold on wait a second 🤔🤔🤔🤔 bmw out here robbing us

[@ruan800]

Amazing video, great explanation, Thanks!

[@Locustandhoney]

Thank you for your good service to humanity!

[@robhughes8516]

Nice diy, thanks for the info and walkthrough!

[@BMWPROGRAMMINGJAMAICA]

Thanks Bro

[@SKWDMDYT]

Thanks for the tutorial. Very well done.

[@BMWPROGRAMMINGJAMAICA]

Thanks Bro

[@markt9438]

I can breathe now even with the garage door closed lol crazy dude

[@timkane1185]

Great video! I’m getting lean codes on my e92, so very timely. Thanks!

[@markt9438]

Best and easiest Explained Lucy ! LOL

[@superspeeder]

Going through the same on a 2011 N52 right now. Original sensors with 200k kms (~130k miles), no codes set, unplugging the sensors brings back midrange torque and improved drive ability and fuel mileage. I thought it was a DISA valve issue, glad I checked O2 sensors first! I just assumed they were ok because no codes were set. OEMs recommend replacing O2 sensors by 100k miles, now I know why.

[@kevinfan2260]

Always helpful. Many thanks!

[@sadiel1]

thank you sir very detailed video and easy to understand

[@LuisGarcia-ye9gy]

Good video bro It helps alot i have a audi s4 and couldnt figure out why it was misfiring i changed alot of stuff still the same. Next its the 02 sensors. Has all this syptoms Thank you! 👍

[@ademc8872]

If you looked at lambdawert katalysator bank 2, you wouldve seen it was way out of whack. Excellent video as always!

[@lucasnl9882]

Thanks for the information. Now I know how to check for bad lambda sensors.

[@yaghiyahbrenner8902]

This is such a great video. thank you.

[@jessicaandtrains7768]

Really great video. I need to check this on mine tomorrow

[@aliyildirim7992]

I swear i love people like you who , i have i think the same problem at 325i 2008 n53 now bc i saw this video and i remember when i changed my sparkplugs and coils and i saw some of them was so dirty and some of them „clean“ like yours , i want to repair by myself what i can because here in Swiss if you go to a service they take to much for nothing and i hate it, but that s the reason exist people like you and youtube to try if we have enough time and we want this to try, big love man P.s from where can i order a usb odb2 cable? Im not the best in cars or repairs but i want to handle what i have , thank you

[@_zz__Z]

Wow! Thank you, I have this issue... I appreciate this.

[@Random.Adventures.]

thank you for the detailed information

[@aidankambeitz6788]

Video helped me a ton thank you!

[@getpaid38able]

😃 great explanation of the pre-cat I have a BMW E65 doing the same thing, tested with ista/d same result, is it possible a O2 can go bad in 3 years? Can something burn out the heating mechanism? Like a recent replacement trans? or a replaced generator?

[@lcagee]

Great video. I like the logical trouble shooting. I’m having issues with my fan on a 93 300e which may have the same 3.2 engine???? My car was almost overheating at 120 while driving thru the McD take out line. The fan I think was off. I would think it should have been on at that temp. The fan was on yesterday. Are there two different signals to the fan??? One based on water temp and the other based on something else? Shouldn’t the fan be on at 120? I am suspicious of my wiring harness on the 93. It is the old brittle one. The wires near the temp sensor look a bit delaminated. Trying to figure out what to do. Don’t want to ruin engine. Probably gotta get that new harness in and hope that fixes it.

[@4037joel]

Wow, ive been driving without 1 o2 sensor for around a year now since i put my DPs on. No wonder i have the same symptoms as yours.

[@tronn_carter]

I thought maybe it was leaky injectors but decided to do a bit more research before buying parts. glad I found this video. mine is running soo rich. crazy fuel smell and white smoke. thought it was leaky index 12s will be changing these sensors, installing new coils and cleaning my plugs as the have less than 100 miles. changed them chasing a misfire issue. only 95k on motor and 106k on chassis

[@brycemacinnis512]

What was your fix?

[@floringiurgiu7454]

What carly alternative are you using on your phone? I.m asking about both the dongle and the software. Thanks :)

[@jadejade5234]

Very informative. 👍🏼

[@EDI-ve1be]

Nice work identifying the af sensor issue. Your long term/multiplication fuel trims are both very negative after the sensor replacement. Did you manage to find the cause and fix for that?

[@HumbertoBenavidesphotographer]

Are you using an OBD enet cable to code or to view parameters on your F15 like you are doing with your E90? I'm very interested because as well as you we own an E90 and a F15. Thanks in advance buddy!

[@raasalghul9211]

Thank you for a very informative video. Please could you tell us what is the app you running on your phone and on your laptop. Are they free to download or subscription based? Many Thanks.

[@TomIves-KingstonWorkshop-]

Awesome video!!

[@ltdasilva93]

Hey thank you for this video, I'm currently changing out my turbos due to blowing a seal on one of them and my mechanic recommended replacing both pre-cat o2 sensors in a pair. They're quite pricey and I was having hesitation issues but attributed it to my wastegates also not sealing properly. To my knowledge the post-cats are ignored now that i'm catless but i will definitely check the voltage on my o2s prior to purchasing them. Also, im not sure if you know or not, but would xdrive vs non xdrive be a problem in regards to reaching the o2s from under the car? I know it's a tight space but worry that the subframe is in the way. Hopefully not!

[@phantom700X]

Thank you. It was useful 👍

[@cryptobeak5108]

Excellent Bro!

[@ncsuche888]

one of the best BMW N54 DIYer! look forward to seeing new video. BTW, will the post cat sensor be easier to change?

[@VehicularDIY]

They are slightly easier to get to, the bank 2 sensor 2 sensor is actually pretty easy to access from under the car.

[@blackhammer6948]

@@VehicularDIY I currently have all new o2 sensors and am going to put in soon and I was curious to know if I have to reset any adaptations or will the ecu just automatically dial in everything after replacing all o2 sensors

[@luisGarcia-wl8bk]

I’m giving this a long shot in hope that you can reply. I’ve been having trouble with diagnosing my car since I bought an eBay inpa software but it is in German. Have very little computer skills and was wondering where you got your software from? I currently have a hp with windows 10

[@skipper3069]

Your video is so explanatory. Need help what inpa cable to use on 2009 335i n54. E92. there so many and some of them don’t work according to users just.

[@aldodelgado5477]

Great!!! I’ll swap mine tomorrow see if that works since I only get a misfire on 2 and it goes away only when I erase the core

[@Random.Adventures.]

You are awesome just wondering if you can show us a demo of the vanos on INPA please

[@hewaabdullah7559]

Very good nice video 📹👍

[@shanedial4985]

Just learning here, bare with me... Cylinder 6 plugs appeared wet when you removed it. Is that gas? Also, will faulty O2 sensors cause gas to collect in the cylinder? Just trying to determine if I have a bad injector in Cylinder 5 (which I get a consistent misfire) or if my O2 sensor in bank two is bad. I have JB4 installed and three days ago I performed JB4 MHD BEF and car hasn't ran right since, primarily at idle/cold starts. I get a rich gas smell when idling.

[@jlindborg1105]

Hi! I actually have the same problem on Bank 2 but I get low voltage values so the engine thinks it runs rich in bank 2. But it gets a little better when the engine has warmed up but still noticeable lower voltages than bank 1. I haven't checked the spark plugs yet but i will. I have the N53.

[@soburnedout]

You mention using your affiliate link for purchases- and I’d LIKE to as you’ve been a great help to me and others, but I don’t see one for the “INPA K+D Can” cable. Please send or reply with the link because I’m about to start loading a dedicated laptop and will want to have the cable by the time the software is ready. Thanks for everything

[@scottxp800]

Full blown misfire mode sets a code and turns off the injector for that cylinder until the next restart. It will try on restart to run the misfiring cylinder again but will again turn off the fuel injector if the cylinder is still misfiring. It was running rough but it was not in full blown misfire mode...

[@Trusty335is]

I recently bought a 2013 BMW 335is 34k miles from Oregon (salted roads) I got codes for O2 sensors. One said too lean and the other said too rich. Are they really bad or could be something else? I have open recall for injectors getting it done in 2 weeks at dealer. Thanks!

[@nadirnazim9342]

I started my car cold and engine started shaking right away. I hooked up a code reader and saw cyl 4,5,6 misfire. I let the car running for a bit more and then started seeing the o2 sensor code. So is it my o2 sensor or something else? When I clear code, I do feel that the engine smooths out for a few seconds.

[@Zsword92]

My voltages are all fine but I keep getting 2CAA Oxygen sensor heater function & 2CA6 Oxygen sensor temperature. All 4 are new sensors . Any ideas? I've tried harness, DME, adaptations, untwisting wires, fuses. Nothing!

[@LALOTEH]

You may have saved me money I was about to order a new set of Delphi coils and 1 step colder spark plugz from fcp my car is running like yours at 2:47 😰 So ima get to ordering the O2 sensors and how to change one on my own

[@humbertor3174]

Is the system you’re using for the codes INPA? Thanks in advance

[@KannieKan]

hey i did exactly what you did in the video. But im still having the same issue, ive looked everywhere online for a solution but im getting a lot of mixed answers. i was wondering if you could help.

[@courtneylane6731]

What code did it throw? I got a P0172. My guy said it’s an o2 sensor issue but I need to make sure.

[@FreedomToYourMind]

nice thank you

[@real_kensou]

Hi ! I have exactly the same problem I think on my x6M (s63) No CEL, no hesitation on throttle, no error message , very slight instable idle, high fuel consumption, pop and bang on cold start, pop and bang on shifting with sequential mode, only black smoke (tail Pipes become black), car has +100k miles on the clock. Do you think my oxygen sensor are faulty too ?

[@johnlira3316]

I have an 04 545i that gave a check engine that says increase emissions any idea what it can be ? It does smoke like urs did guessing its running too lean or too rich

[@olenairsoftguy88]

great great great video!

[@dfqnexxus3710]

I hace exactly the same car 08 335i with 190k miles and I have mixture control on bank 1 and 2 also fuel pump pausability and most of time long cranks, replaced fuel pressure sensor and fuel regulator and still having this issue , any recommendation ?

[@teccmo]

I have same issue with a 2009 n52, 328xi. I've changed plugs and bank 2 coils. I'm trying to figure out if its the o2 sensors that are causing the misfire codes (only on bank 2) - and for some reason it says catalyst efficiency is below threshold?? on both cats. the numbers look ok for o2 sensors i guess, except on the bank 2 mix, it's adding a lot more fuel than its supposed to in the long run. little help?

[@amzlife0319]

Hey man, which 02 spacer should I get for bmw b58 catless downpipe. Please send link, I am so lost 🙏🏾

[@asankovlogs]

Have 2c7f and 2c6c oxygen sensor codes Are they gonna cause any problems to the car? E90

[@emmanuelenriquez4872]

I'm currently having a really bad misfire, getting 2c7c lambda behind and 2c2e in front of catalytic and cylinder 6 misfire. Would that mean both sensors on bank 2 gave out? I also have jb4 tune and can't get rid of code

[@mohe81]

These air filters are positioned perfectly xD

[@QuanNguyen-vi1fi]

Will it cause the limp mode in my 07 E70? I am having random limp mode regardless driving style/load/speed. I have replaced camshaft sensor, vanos solenoid, eccentric shaft sensor and disa valves. The code I pulled up is 2c31.Thanks

[@datlyfestyl3905]

Have you ever had an issue when you start your car up and immediately your car starts to rev up and down repeatedly and when you step on the throttle it’s not responsive? When you put it on drive car still won’t accelerate but starts to jerk really rough?

[@michaelaguirre3668]

I’m having a similar issue I put all brand new Coils and spark plugs but my cylinders 1-3 are still misfiring and my spark plugs are wet with gas when I take em out so you think my O2 sensor Is the problem .?

[@isrealperez9069]

So on my 04xi I have negitive fuel trim precat bank 2 can rear O2 cause precat to go bad

[@wichafroggy]

Just did this to mine. But now something cracks when I turn the steering wheel. Could it be my steering rack not Being aligned right?

[@BMWI-gk9wh]

Fyi to save some money the o2 sensors are the same along as you get 2 rear ones (2 extra long ones will work but wont work viseversa... meaning two short ones obviously wont work and would cost way more for the short one vs long one meaning bank 1 vs 2 )

[@RHYMVIBE]

Thank you...

[@samuelnemetsky4088]

Where is bank 2 sensor 2 located? I can't seem to find a DIY on this at all.

[@Linoge279]

for bank 2 sensor its located on header for cyl 4,5 & 6 right?

[@friguy4444]

Well I'm back about 10 months later and I have bought an E90 2008 335XI. (I still have the E46 M3 too). But I fear greatly that the O2 sensors need to be replaced on it as the car is having horrible cold starts with misfires on first 1 and 3 then if it is a bad cold start it's even more cylinders. One code read showed oxygen sensor code. The coils

[@mr.valentino2824]

I'm have what I think may be the same symptoms on my X5 xdrive50i. My code is 2D0D. Would you happen to know if this is the same? The code comes up on carly as air mass 2 Plausibilities or air volume 2 Plausibility.

[@workwithjp170]

I have a 29E1 code that pops back up every day or so. I just keep clearing it to try to narrow down the issue. I have a rough start in the morning after it’s been sitting all night but otherwise my starts are pretty smooth. Once it warms up, it smooths out too. I thought maybe o2 sensor but if it doesn’t give me issues warm, should I look more at injectors instead? I have also gotten a cyl 5 misfire every now and then, so I’m leaning towards injector in bank 2.

[@twinturbo8304]

Can’t we just wire the exhaust flaps open or will that mess something up?

[@martijndaemen4834]

when you disconnect the sensor on a 318D, will it have the same effect? cause it also run bad only in idle and i don't get a engine light. greeting from Belgium! great video!

[@martijndaemen4834]

it's a N47 engine btw

[@manuelamaya826]

Thanks.

[@erickromero010]

i’ve been running them backwards and running rich for about a month ugh i need to switch them! i forgot to mark them when upgrading to catless downpipes

[@raymartinez5327]

I have an 2007 335i and I am getting a u30b7 any ideas on what it can be ?

[@jakubkaminski874]

Can u paste here the part number for bank 2 pre cat lambda that u have replaced? I am about to buy one and I really dont want to get a different one :) I would really appreciate that