I wish I Knew EARLIER! Post Cat Oxygen Sensors | BMW E90 DIY

In this video I show you how to replace your secondary or post cat oxygen sensors on your N54 powered BMW. I am working on my 2008 BMW 335i.
This video shows you how to save some money by using universal Bosch sensors instead of paying the premium of sensors made for the car. The head of the sensor is the same and it is OEM quality.
We get into some theory as to why they are important on modern direct injection cars and discuss how they can improve how your car runs. They are not just to sense if your catalytic converters are healthy.
You can purchase the sensors here (affiliate):
amzn.to/306Vq6f
I know I neglected them thinking they weren't important but learned how valuable healthy secondary oxygen sensors can be for your car. Consider replacing them if they have a lot of miles on them, even if you're running down pipes.
Thanks for watching! 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!

[@black51789]

YOUR THE BMW N54 DIY KZbin KING

[@abdul_adi]

While I was doing an oil change today I noticed that the wires on my downstream o2's were burnt to shit. I didn't think much of it because I had no engine light. It's such a coincidence that I got this notification RIGHT as I finished. Definitely going to change them out ASAP, thanks for the informative vid!

[@khoirunnisa8904]

Lfofkhfj

[@khoirunnisa8904]

0rititirirj

[@JasonLitman]

Wish I had watched this earlier lol. So helpful, and I’m replacing my n55 post cat. All makes sense now!

[@AlexanderMatosOlivo]

I'm a new commer to your channel and I have to say, you explain all with such clear and simple way that I can't see another channel with such a good content.... keep the good work man, excelent and accurate

[@mtechk6034]

I Totally agree with you bro 😎

[@omegadevil22]

Awesome I have e92 and plan on hooking up all sorts of stuff based on all your videos

[@KrzysztofCygan]

There is a sensor test menu/procedure in INPA (I think under F9), it tests O2 sensors and shows resulting Min and Max values for all of them, narrow and widebands.

[@user-uv6ri7qb4g]

Hi Cygan, could you help me identify which 02 sensor is bad in my case ? Here are the values which differ : *multiplication adaptation: bank 1: 30.443% | bank 2: 4.211% *correction injection time: bank 1: 5.66% | bank 2: 1.34% *lambda voltage after catalyst: bank 1: 0.13v | bank 2: 0.78 v Thanks a lot !

[@joyroc885]

I'll keep this in mind once I find my 335I project car. :)

[@noahgreen8610]

This is a ultimate life saver in prices thank you so much will definitely be using your link thanks.

[@sulimed]

Just got finished doing this a minute ago and it worked like a charm. You are the man!!!!!

[@Itsnotimportantbud]

What was your issues before doing them?

[@sulimed]

@@Itsnotimportantbud they didn't work

[@kamilozw86]

Great Job. Soon I would like to buy a e92 and your videos helped a lot to prepare for some work on car. Keep going like that.

[@nickolascain2994]

Yeah, I figured it was only post cat related. Didn't know it influenced the wideband. Makes sense... Thanks for sharing!

[@slick2k829]

Outstanding. I think this is my issue. Thanks for the explanation!

[@n54sparrow92]

Just bought the same set off eBay for my 135 2009, way cheaper than the original with the full harness 👍 thanks for this video and the full explanation

[@loki8434]

Is the post cat O2 sensor located the same as the video?

[@walkereurosport944]

Always informative 😌👌

[@abdulhaqqhaiti]

Love your explanation, you're my guy. Keep up your good work

[@Kipitrl]

Great videos! My turbos arrive tomorrow:)

[@friguy4444]

From what little I am understanding about what you're showing us. This all happened because the person that did your "DP Fix" didn't put it back together quite right a crossed two wire pins and instead of oin 19 and 20 being in their correct places they were crossed and 19 was in the spot where 20 should go and Visa Versa? But I learned so good stuff from this as well like some of the relations between the two sensors and what they might be doing when trying to adjust and measure your levels of Oxygen etc. The O2 sensor mod to save money is a great bit of info. Thank you again for the helpful video.

[@abdulhaqqhaiti]

You answered my question in your well explained details..thx dude

[@andyridley2236]

Very good,so many people have problems with these sensors because they do not understand them.

[@MrNicoe36cabrio]

Again a very nice tip!

[@reginald8405]

Great video, learned a lot.

[@jorgebeltran5703]

bro killer content and is very helpful.👍keep up good work.

[@hammadrehman4257]

I don’t own a 3 series but 5 mins in I sub’ed.

[@jessicaandtrains7768]

Swap at 11:08 👍 Nice work. Have to get money done. Codes on bank 2. The one that's a pain to reach. Otherwise a 10 min job. Wish they'd consider access more in future.

[@tazwinsulose]

Thank you so much! After installing new 17T turbos with catless downpipes I haven't been able to get rid of air/fuel and 02 codes. Have misfires etc. I'm going to do this and get back to you with my results. Thanks again for all your videos. You've been a great help for ALL of my mods.

[@waterdogxx7871]

So?

[@chtistianvasquez6029]

And ?

[@tazwinsulose]

@@chtistianvasquez6029 YES! It's been running perfectly. No codes. AFR's reading right. Also installed XHP stage 2. Thanks again for the help on this. Really saved me after all the work.

[@TimelessMotors]

@@tazwinsulose so all you did was replace secondary o2?

[@tazwinsulose]

@@TimelessMotors Yes but you have to use Bosch# 15733 for both and splice the wires to the or plugs.

[@MrGerdar]

Great video instruction

[@pennypacker2000]

love your videos man ,top stuff! .. what is the connector thing used to connect the wires together?

[@machtschnell7452]

Super infornative. Might have done a normal speed on the first wire or two for us slow ones.

[@kentjones9178]

Very informative & well explained. For my 2008 335i (108K miles), my bank 1 cylinders are throwing misfire codes and I get rough cold starts. Indie shop says my injectors are bad. I can believe that but think I have an additional problem related to my bank 1 secondary cat sensor. On car scanner, bank 1 sensor 2 output voltage dithers from .05 to .85 volts and never reaches steady state at any engine rpm. Bank 2 sensor 2 acts as expected - it varies between .8 and .4 volts with engine rpm. I’ve replaced both post cat sensors now and bank 1 still dithers at about 1 HZ. Just had my car emission tested & passed with no issues. Do I have a potential cat problem on bank 1? Any thoughts would be appreciated.

[@shafieksalie3119]

Thank you 😂👍👍👍

[@glennshimamoto9922]

Thanks for getting me to check my pins 19 and 20 which I had swapped when removing DPFix. This was the central cause of all my bank 2 misfires and continual rich conditions which caused me to replace 3 injectors and plugs and consider replacing all my O2 sensors. Essentially this wire swap error caused the postcat O2 sensors to be mismatched with the primaries. LTFTs and STFTs are now in bounds. Still trying to resolve a 29E1 however but the car seems to be running strong.

[@n54hamzeh58]

Hey what are Pins 19 and 20 where are they located on the DME I did the DP fix as well and I’m having this problem

[@glennshimamoto9922]

@@n54hamzeh58 Pins 19 and 20 are yellow wires in the small black connector in the DME area that you temporarily extract. To install the DPFIX, you insert the DPFIX black female wires into these positions. Record which yellow wire originally went in the 19 and 20 pin position, so they can be correctly reinserted when the DPFIX is removed. If they are swapped, I believe you will get codes saying the O2 sensors are swapped. I ended up replacing all my injectors with Index 12s and this resolved my misfire problems.

[@soundmasterx]

@@glennshimamoto9922 thank you for the info. Just to be clear, is it no longer recommended that we use the dpfix? I've been out of the scene for a minute, but I'm now installing a ST kit so I'm trying to catch back up. Thank you for taking the time to answer our questions.

[@pawlygunnz2065]

Could you explain to me how you swapped 19 and 20 arent they the exact same jumper wires?

[@jerrythomson1661]

thank you very much, hey from russia

[@BimmerTV]

Thanks for the in-depth explanation on this. Keep the videos coming. Side note: The volume is a little low in all your videos. Try a mastering plugin or some compression on your master channel to bring up the levels a bit.

[@BimmerTV]

Good money saving tip too

[@c.c7263]

Great video as usual! But, I think you should talk more about how you swapped the wires with your ECU and what the issue was exactly with upgrading to MSD81. I just upgraded to MSD81 and I am having error codes that I didn't have before (misfires in inj 2-3-4-5 and mixture control 1 /2). I am suspecting that there is an issue with the wires with the new ECU...

[@giovannifernandez2258]

hello I have a question when you put new turbos without tune you can pass the smog test?

[@godla26]

Great video I have same issue and I am about to do same job but my question is you used same sensor for bank 1 and 2 or there is different part number? Because Amazon showing package of two with 2 different part numbers like 15733 15730 But 15730 shows that it does not fit the car. Is all sensors same size treat and same voltage for the rear and for the front? Do I purchase same part number that you showing for both side bank 1 and 2? Thanks

[@jakestar77]

So, I’d like to replace both of my post cat sensors. Can I just get X2 of these universal sensors? Or do I need a different one of the the 2nd sensor?

[@brunomachado237]

I got the same symptons then you! Just after replace my spark plugs. Then I follow your steps, initilly checking the DME mosfets, there I found one damaged. But while I'm holding the shipping of it, I believe that my BANK 1 sensor are also bad... CODES P0300, 301, 302, 303, P10A5 and P323F are there. I'm ready to order the 4 O2 sensors to solve it... do you think that it will be enough to solve my codes?

[@therrandy2506]

Good Video. X5 next?

[@luyanoH]

Do these sensors work for before and after, I'll be getting my Doc single in about a week and i was thinking replacing all 4 for the fun if it, I'm at 120k miles. BTW I love your videos since I do all the job by myself. I just installed a twin clutch with jack stands :P

[@shaunpilkington4625]

I’ve had post cat O2 sensor codes ever since I have my clutch replaced a month ago.. time to get under the car and have a look why..

[@kennethharrison9293]

I had downpipes installed on my n54 2013 335is get check engine light every morning if I change the O2 to the ones you're talking about in your video will that shove my problem and do you have to change the ECU Thanks and great video.

[@jasonhiggins1012]

Do you know if this universal O2 sensor would work on the N55 downstream sensor?

[@justinmcgee35]

I have an 07 335xi I’m putting catless down pipes on next week. Would you recommend changing the 02 sensors then to this conversion? It’s the MSD80 ecu, and I have 129000 miles.

[@khalidmangal9870]

These are not available on the link you have posted. Can you update the link to where I can purchase these please. Thanks!

[@Boosted_Gramps]

Hey bud. I have a lean condition on bank 2. On wot the car lights up the service engine soon light. Codes shoe cyl 5 and 6 misfire. I have done compression test, change the coils and injectors around with no change. I was wondering if the rear o2s are the issue. Car starts fine, idles fine but sometimes has long crank after daily driving. Hpfp and lpfp pressure is good also. Been chasing this around for a while. Also im using a custome tune e50.

[@jayvee8948]

Hi, I’ve been watching your videos because I’ve been chasing some misfire and rich condition with my e92 N55 engine. Would this work for my car as well? Do you have another link for the primary 02 sensor as well?

[@kevinkalil147]

Hi there. Maybe you can help. I have a bmw 550i and It is running with negative fuel trims. Its running very rich and even smoking. I replaced precat sensors and didn’t help. I recently got the code P114B and P2196. No misfires so far, i back my car into the garage and the wall has black carbon on the walls coming from my exhaust. Should I replace secondary sensors?

[@alexmercado3361]

Wonder if this is why my single turbo setup is giving me fuel trim codes. Both rear o2 sensors are in a single 3” exhaust post turbo. Would moving the rear o2s to the manifold (separated by bank) fix my fuel trims issue? I’ve notice I have to reset my fuel trims every so often or the car will drive like crap.

[@daledog16]

What app/software you using to clear codes and adaptations?

[@Foreignsgarage444]

Probably a dumb question but can you use theses on the top stream if tho they down universal ones

[@christopherreus7799]

Nathan a little confuse. if I buy the ready to go ones are they narrow band ? Or wide band the same as those you did

[@roblesinline6642]

I’m having issues with high rpm hpfp dips but hpfp is new did u have this issue ?

[@NWABIMMER_KEV]

Are these the same sensors for the primary too? Or is it only for secondary?

[@dbdb4665]

Can an oxygen sensor be faulty without reporting an DTC? What is the best way to test it, can it be cleaned maybe? I have problems on cold start for a few seconds the idle is rough, and afterward everything is good i would say. All glow plugs are changed and the relay too. The car is E91 LCI 318D 105kw 11/09, it has only 1 oxygen sensor I would say only on the DPF, next to the temperature exhaust sensor and the pipe for pressure sensor. Thank you for the answer in advance.

[@joegarcia8447]

Hi I’m getting 29eo code in my 08 bmw 335i do you think it might be an o2 sensor thx or secgestions 😊

[@KingLlovit]

Hi bro, im getting 2C40 code and im confused if I need to change my old MSD or I will change my o2 sensors. AFR Bank 2 reading is stuck at 20. any suggestion?

[@goldenace716]

Whoa wait, should i be resetting adaptations after replacing these sensors??? Is there also an adaptation reset for MRS, specifically for your BST? I have a 2D0D (P0030) AND 93B2 (Battery Security Clampe). I've replaced the upstream O2 sensor (N55) and my Battery Safety Terminal to help fix the codes but they haven't gone away and when i try to reset them, they just come back

[@marknguyen3772]

Did you have catless dp's at the time of this vid?

[@OzzyTheFerret129]

Hi went from. msd80 to msd81 now 02 will not set to be ready for emissions do I have to swap any pins on the dme

[@christianmedina9908]

I got a 12a902 code. already changed the up one but still getting the check engine should I change the second one ?

[@vinnycorleone7446]

Im getting 2C7C which one do i have to replace ?

[@adrken2008]

When does DME caibrate primary sensors with readings from secondary sensors? at WOT?

[@maxmeekhoff]

Did you code out the SES light?

[@michaelViking]

Can I use this part number for primary as well?

[@FrankBernal24]

I also have an 8 335i. I replaced the MOSFETS in mine. After replaced I'm getting very rough idle and code p0174. No other codes. Car is pretty much undriveable. Maybe replace bank 2 sensor? (p0174 is for bank 2) Ive done a smoke test to check for any leaks and nothing. Any help is appreciated. Thanks !

[@shanebroom9173]

Im still using my msd80 ecu and after i did the mosphet upgrades and did the carless downpipes i put o2 spacers on the rear o2s thinking id have luck getting it to pass for emissions but later found out i just ruined the rear o2 sensors so im about to do this cause i have the same codes you're throwing in this video and if my msd80 ecu is telling me this same issue it must be pretty bad but i need to get this car fixed cause if not i wont have tags for 3 months saving up $500 for the 4 o2 sensors but now i think i just need 2 of them based off this video so gonna try this and see if it fixes my issues and take the caps off the o2s and not reinstall them on the new ones but based off how you explained it it makes alot of sense as to why this is happening now and why it feels like my car is at loss for power cause it is

[@tasoskroustalis]

Hi! Finally did you fix the problem with this way? I have the same issue and I put O2 spacers too.

[@redihoxha2940]

Why you replaced both downstream sensors? Wasn't enough one of these? I have P114D(pending)

[@John.Azucena]

my 07 e92 throwing a DME active code of 2C32 & 2C6a and 2C6B, But I got no engine light, it does turn on time to time. Car is on a MHD stg 1+ tune with oem DP, not sure if I should worry about this.

[@boujiiyt5363]

So you used the same sensor for both upstream and downstream post cat??

[@erickromero010]

I have these same codes after new hpfp on mhd 2+

[@raphaelpmcurvo]

the post cat lambda are 4 wires and how many ohms ? i think this is universal but just in case

[@mattporto4530]

I’m having this issue with my BMW, i replaced the big Disa valve (1) and catalytic converters and all the lights were gone, but now is giving me another code, 002AAC. The Big Disa valve is new, the small one I checked too and it’s pretty good, I even did the active test with the scanner and it seems to work, but while reading the live data of my sensor, it kinda looks weird, could that be my issue? Thanks

[@giovannipoorsaid1744]

This is funny lol i got the msd81 as well yet im still having misfires but i dont have o2 sensor codes i have misfire for 5 and 6 i also have dme mixture control 1 & 2

[@billyowusu48]

Giovanni Poorsaid new injectors?

[@noahgreen8610]

Anything for the pre catalytic O2 sensor replacement for cheap

[@miataworks]

How do you reset o2 adaptation? I left dp fix too long now I can't get rid of lean code on 1 bank. Thanks.

[@n54sparrow92]

Could this fix my issue for 29f4 / 29f5 just have these code as shadow codes and car burns more fuel just started happening to me

[@Kenny_Blanco]

I know that this was an old vid. But great content & info. Hopefully I can get my check engine light to stay off after replacing my rear O2 sensors. I’ve already replaced the front if I need help with removing my DP fix. Would you be able to pint me in the right direction. Thank you kindly

[@user-qn2di7nl9n]

Hello how are you sir how much the price of a wire kit for MBW 382i ​​2008

[@misterp4047]

Ok i gave replace them and follow your video and copy it but i have codes 29F4 and 29F5. It is not showing on my dash but when i read codes with MHD. Help me bro, do you have these code olso

[@mattmartin5757]

Where’d you get that key case at

[@abdulhaqqhaiti]

Hi there, can these be used for pre cat ?

[@redihoxha2940]

My error is P114d, indicated B2S2. I have to replace both of them? ✋

[@zeljkoc5068]

Hello Guys! is this works for other models? I have E90 320i with N46 Engine. And can I change only one sonde?

[@khorvath74]

I replaced my (e90 318i) NOx sensor and reset the adaptations, before with the faulty sensor I was getting only one fault code 3104 now with the new one im getting two fault codes 30DC and 30DE. Why? Injector, sparkplugs and coilpack all brand new. Help pls.

[@Cdswjp]

great

[@bloodsUYA]

Bank 1Sensor 2 oscillates nonstop 0.9v - 0.1v and bank 2 sensor 2 oscillates at a steadier rate around 0.5v - 0.4v . Which one is bad?

[@shanebroom9173]

Can you do this for the front o2 sensors aswell cause i can get boshe lsu 4.2 or 4.9 o2 sensors for $62 a piece and $125 for 2 o2 sensors is alot better than me getting the two sensors from fcp euro for $250 please let me know i imagine you can i just really want a second opinion

[@audunjemtland8287]

Such an amazing video. Thank yoooou!! Can they be cleaned instead?

[@bronxbmw625]

You ever get a 2c27 and 2c31 error codes i replaced my precat sensors but still show up

[@twinturbo8304]

Hi I watch all your videos I am installing catalyst downpipe’s and intakes and charge pipe and intercooler. Am I going to have a problem throwing codes I have a JB plus tune? Thanks

[@VehicularDIY]

Thanks for watching. No you should be good.

[@twinturbo8304]

I wasn’t going to try to put intakes in until I saw your video. I got them in after a battle but I have a lift which makes it much easier, thanks again

[@juanmckenzie524]

Where do you get a new ecu?

[@mauricioleal3571]

Did you use the same sensor for both sides?

[@spiritsavage]

That's all great and all. But even with a new O2 sensor after my tune, it's still triggering the CEL. Does a bung spacer affect the engine badly at all? Or what can I do to keep the CEL from throwing that code?

[@skylinefever]

There are a few rules to remember whether you have a BMW or not. It is important to know the brand of the OEM sensor. Sometimes when a Denso or an NTK is replaced with a Bosch, it makes the car run poorly. I suppose the same thing could happen if a Bosch was replaced with a Denso or NTK. However, I have never had a problem replacing an NTK with a Denso or a Denso with and NTK. Universal 4 wire O2 sensors have another benefit. Some very old cars had a one wire oxygen sensor. It would take longer for the sensor to warm up and start reading. With the right conversion kit, you can get that sensor to work sooner. Building something to properly heat that sensor requires some special wiring. The need to convert heated oxygen sensors becomes more important when replacing iron manifolds with long tube headers.

[@elcucuy8635]

Question could I use this part number to replace all four sensors

[@shanebroom9173]

No youd have to find a universal wide band sensor that would work for the primary sensors the part number provided is for the post cat o2 sensors not the primary im going to go look on amazon and see if i can find a Wideband o2 sensor thats universal so you have to wire it and see how much it cost upside the factory units that are nearly $150 each

[@MrSexgeneral]

Are those the same exact sensors

[@mymemories925]

My obd2 reader claims bank 1 system to rich PO172, HAVE REPLACED UPSTREAM SENSOR, EML LIGHT CAME. BACK? SHALL. I CHANGE DOWNSTREAM SENSOR? IS DOWNSTREAM BANK 1 UNDERNEATH CAR? ANY HELP APPRECIATED THANKS

[@nogueirar3716]

Hey bro I’m getting the same codes but I also have 3 misfires cylinders 1,3 and 5. I have ordered 2 step colder spark plugs and am planning to get new coils too, the issue I’m getting is the code and I when ever I start up the car it’s has a rough idle and throws the codes Oxygen sensors after catalytic converter: mixed up Cylinder misfire 1,3 and 5. I tried swapping my coils around to see if the misfires follow but they don’t. I have been stuck with these codes since I put in 3inch cat less downpipes, I have since replaced my primary o2 sensors and have gutted my oem downpipes and installed those I think the post cat o2 have been damaged during the change of downpipes. What do you think I need todo. Do secondary o2 sensors plan as much of a role that it will make my car idle all weird and make it misfire in multiple cylinders ?

[@nogueirar3716]

Sometimes I reset my lambda adaptions before I start and the car will have the codes but still drive normally without a jumpy idle

[@EYES2CU]

Will this work on 2004 e60 upstream it an M54 engine