Pre cat o2's

[opihi5]

Anyone know of a solution to the precat o2's failing non stop. I've been buying Bosch replacements and they only last a few months. Seems like its pretty common for these to go out....

[dparm]

Originally Posted by opihi5

Anyone know of a solution to the precat o2's failing non stop. I've been buying Bosch replacements and they only last a few months. Seems like its pretty common for these to go out....

Is your car tuned or something? Oxygen sensors should last a pretty long time.

[Dave07997S]

Originally Posted by opihi5

Anyone know of a solution to the precat o2's failing non stop. I've been buying Bosch replacements and they only last a few months. Seems like its pretty common for these to go out....

Not at that rate, how are you doing the install. Are they unclipping them before removing so they don't twist the wires, don't let them bang together. Also, buy from FCP with their lifetime warranty.

Are you running a tune?


Dave

[opihi5]

Yes i’m tuned. Not sure why that would make a difference...if heat is the problem thats why im looking for a solution.
I unclip them during install to prevent wire damage.

[E92_Toronto]

Originally Posted by opihi5

Yes i’m tuned. Not sure why that would make a difference...if heat is the problem thats why im looking for a solution.
I unclip them during install to prevent wire damage.

Are you running a burble tune/flame map ?

[msan]

What codes do you get to tell you they are out?

[opihi5]

Originally Posted by BramptonE90

Are you running a burble tune/flame map ?

The failures all happened on evolve 91 tune. I'm getting heater resistance codes for the pre cat banks and car will throw a service engine light(not check engine).

[kabeero]

hi,

I'm having similar issues with stock S65.

I had a pair of Precat Bank 1/2 O2's last for 50k+ miles, replaced both and Bank 2 has failed another 2 times in 8 months.

I RMA'd one sensor because it failed in about one month. and the replacement has now failed within 6 months. do you suspect these are now being manufactured poorly?

I don't have issues on the new Bank 1 sensor or any codes for misfires, insufficient flow, or engine mods.

[kabeero]

Originally Posted by msan

What codes do you get to tell you they are out?

274B : Oxygen sensor bank 2 (lambdasonde pumpstromabgleichfehler vkat bank 2)

P2629 : O2 Sensor Pumping Current Trim Circuit / Open (Bank 2 Sensor 1)

bank 2: driver side
sensor 1: precat

[dparm]

Originally Posted by opihi5

Yes i’m tuned. Not sure why that would make a difference...if heat is the problem thats why im looking for a solution.
I unclip them during install to prevent wire damage.

It would absolutely make a difference. Tunes produce more power which means the explosion generates more heat. That heat is directed out the exhaust, and obviously the O2 sensors can't take it for very long.

The first troubleshooting step I would take is to run without the tune for a while and see if the sensors continue to fail, assuming the sensors are being installed correctly as others have mentioned.

[opihi5]

Originally Posted by dparm

It would absolutely make a difference. Tunes produce more power which means the explosion generates more heat. That heat is directed out the exhaust, and obviously the O2 sensors can't take it for very long.

The first troubleshooting step I would take is to run without the tune for a while and see if the sensors continue to fail, assuming the sensors are being installed correctly as others have mentioned.

It only seems to happen after driving hard for awhile so that makes sense and the codes usually go away after clearing. both sets i've gone through lasted about 2-3k miles before giving me problems. Guess i'll just have to keep replacing o2's if there aren't alternatives.

[dparm]

Originally Posted by opihi5

It only seems to happen after driving hard for awhile so that makes sense and the codes usually go away after clearing. both sets i've gone through lasted about 2-3k miles before giving me problems. Guess i'll just have to keep replacing o2's if there aren't alternatives.

That seems like an absurd waste of money for a few extra HP from a tune. Even if the sensors are $50 each, and you change them 4 times a year, that's $200 in parts alone -- plus the labor/time to do it, ordering another one, and the aggravation of wrenching on the car for an hour.

Have you talked to the tuner to see if they can check things out? Maybe the tune is too aggressive or something? Do they suggest using O2 sensor spacers?

[opihi5]

Originally Posted by dparm

That seems like an absurd waste of money for a few extra HP from a tune. Even if the sensors are $50 each, and you change them 4 times a year, that's $200 in parts alone -- plus the labor/time to do it, ordering another one, and the aggravation of wrenching on the car for an hour.

Have you talked to the tuner to see if they can check things out? Maybe the tune is too aggressive or something? Do they suggest using O2 sensor spacers?

Would o2 sensor spacers change the afr reading if they are on precat o2's? Might have to look into them.

[Dave07997S]

Also, did you check for an exhaust leak from the header to the xpipe?

Dave

[yidgyi]

I've been running Gintani's burble tune & the new extreme burble tunes the last 10k miles. Car just hit 67k miles original O2 sensors for whatever that's worth.

I don't want to insult your intelligence but are the 02 sensors being installed correctly? Also, as Dave mentioned if you have an exhaust leak from the header to test pipe/xpipe it can cause all sorts of weird issues. When installing my catless system I used wrong gaskets and it gave me codes of all sorts related to o2 sensors and misfires.

[dparm]

Originally Posted by opihi5

Would o2 sensor spacers change the afr reading if they are on precat o2's? Might have to look into them.

In theory, yes, because they move the sensor slightly out of the stream.

[eatsleepboost]

Originally Posted by dparm

It would absolutely make a difference. Tunes produce more power which means the explosion generates more heat. That heat is directed out the exhaust, and obviously the O2 sensors can't take it for very long.

The first troubleshooting step I would take is to run without the tune for a while and see if the sensors continue to fail, assuming the sensors are being installed correctly as others have mentioned.

What about us that have superchargers and are not running through o2 sensors? We are making way more power than a tunes m3. The power and heat are not related. I over doubled the power on my last car with Bosch sensors and the manifold would glow red it got so hot and the front o2 sensor 8 inches away lasted years.

Op what fuel are you running? Any chance you have put leaded fuel through the car or e85?

Edit.. just saw you are getting heater codes. That has nothing to do with the flow of exhaust across the sensor. That is simply a heater that warms the sensor up to operating temperature.

[Richbot]

Seems like the heater circuit is the problem on the car side rather than the sensor if it's repeated with new sensors, quickly, if that hasn't been eliminated yet

All of O2 my sensors are original and the car has had an Evolve tune for like 90000 miles. Doubt it's the tune. We have thousands of tuned M3's out there and eating precat O2's is not such a common problem unless they're all hiding out where the people with catastrophic DCT failures are hiding, and multiple inexplicable failures is definitely not commonly reported on here

A) try a genuine BMW replacement, just to make sure, sometimes parts get transposed and marked wrong and it could be a bad lot and you're buying from the same bad lot over and over
B) troubleshoot the car side of the heater circuit

Not necessarily in that order, that's what I'd try, if I was just a dumb guy in a home garage with a scanner, which I am

[opihi5]

Originally Posted by Richbot

Seems like the heater circuit is the problem on the car side rather than the sensor if it's repeated with new sensors, quickly, if that hasn't been eliminated yet

All of O2 my sensors are original and the car has had an Evolve tune for like 90000 miles. Doubt it's the tune. We have thousands of tuned M3's out there and eating precat O2's is not such a common problem unless they're all hiding out where the people with catastrophic DCT failures are hiding, and multiple inexplicable failures is definitely not commonly reported on here

A) try a genuine BMW replacement, just to make sure, sometimes parts get transposed and marked wrong and it could be a bad lot and you're buying from the same bad lot over and over
B) troubleshoot the car side of the heater circuit

Not necessarily in that order, that's what I'd try, if I was just a dumb guy in a home garage with a scanner, which I am

1) 2743 Lambda sensor heater resistance diagnostic VKAT bank 2
2) 2742 Lambda sensor heater resistance diagnostic VKAT bank 1

I've never heard about this. Would it be a simple fuse to fix or serious electrical work?

[SYT_Shadow]

I've been tuned for a combined 150k miles and never gone through a O2 sensor.

I see how a burble/fire tune could change that, but if you have a regular tune you should be just fine

[dparm]

If it's the heater circuit, then this is a completely different discussion. This is why it helps to post the exact Pxxxx codes.

[P1zzaboy]

I have the same exact problem! Replaced b1s1 3 times

Now both banks are gone at the same time...

P2626 and p2629 codes