[tej98]

Hello, I've been getting code 29E0 during cruising conditions which I see is indicative of bank 1 running lean. Bank 1 has all index 12 injectors that I bought used back in October (with ~38k miles on them) to replace my old leaky set on that bank. They have been fine since then and I recently checked the plugs again and found no fuel on them so I know they are not leaking (I assume they could fail the other way and not flow correctly however). This code just started a few days ago as well. Below are logs at idle, a 3rd gear, and a cruising log.


The car is a 2009 335i 6MT running MHD v9 Stage 2 with the supporting mods. All the vacuum lines, TMAP, spark plugs (NGK 1 step colder at 0.022"), charge pipe, and VRSF 7.5" intercooler have under 10k miles on them.


My observations are that idle STFTs are fine, but bank 1 LTFTs are high at ~22%. Under the 3rd gear log LTFTs are near 0 (which I believe is normal) but STFTs on bank 1 begin trending upward, but do not near the limit of 34%. Another note is that my LPFP is showing weakness towards the end of this log, but it does not make sense that this would impact only bank 1 (atleast I think). The cruising log is interesting as bank 1 STFTs do not go above roughly 13%, but bank 1 LTFTs are once again ~10% higher than bank 2.


I have no idea how old the oxygen sensors are but the car does have 106.5k miles on it. Does it make sense to change the upstream sensors or are these symptoms indicative of other issues?


Idle Log: https://datazap.me/u/tej98/idle?log=...18-19-21-22-23

3rd Gear Log: https://datazap.me/u/tej98/mhd-v9-st...18-19-21-22-23

Cruise Log: https://datazap.me/u/tej98/cruise-1?...ta=18-19-22-23


Thanks in advance!

[Sgop335]

Fixed this code recently only during cold start up in a round about way. Also ethanol was involved.

For starters, tried lambda regulation adap?

[tej98]

Originally Posted by Sgop335

Fixed this code recently only during cold start up in a round about way. Also ethanol was involved.

For starters, tried lambda regulation adap?

Thanks for the reply!

I actually just cleared codes and reset both lambda adaptations in MHD along with the intake air metering one. Interestingly enough, the same behavior in trims was present (I have yet to examine the logs), but a difference in the cat conversion codes instead. Typically the two cat conversion codes for both bank 1 and 2 show up at the same time. Instead the cat conversion code appeared for bank 2 and not for bank 1 at all yet.

This leads me to believe there is a lazy oxygen sensor on bank 1. Does that logic seem to make sense or is it out of line? It seems those specific codes for either bank always appear together after a code clear.

[Sgop335]

Originally Posted by tej98

Thanks for the reply!

I actually just cleared codes and reset both lambda adaptations in MHD along with the intake air metering one. Interestingly enough, the same behavior in trims was present (I have yet to examine the logs), but a difference in the cat conversion codes instead. Typically the two cat conversion codes for both bank 1 and 2 show up at the same time. Instead the cat conversion code appeared for bank 2 and not for bank 1 at all yet.

This leads me to believe there is a lazy oxygen sensor on bank 1. Does that logic seem to make sense or is it out of line? It seems those specific codes for either bank always appear together after a code clear.

Also Forgot to mention the lpfp pressure is too low.
Not sure I understand you, but after the adap reset is the code back? Also thought there is only one code, above quote refers to codes...

[tej98]

Originally Posted by Sgop335

Also Forgot to mention the lpfp pressure is too low.
Not sure I understand you, but after the adap reset is the code back? Also thought there is only one code, above quote refers to codes...

Yeah, I also noticed the lpfp pressure is low towards the end of the pull but not really during the cruising logs which is when the code is thrown.

So the original code present was for the mixture control. After clearing codes and resetting adaptations I noticed that the typical cat conversion codes (that are usually present in our tuned cars as shadow codes with MHD) were only present for bank 2 so far. Usually both bank 1 and 2 appear at the same time as the oxygen sensor monitor sets, but bank 1 appears to be lagging a bit now. This leads me to believe that bank 1 oxygen sensors may be lagging compared to bank 2, which is why the bank 2 cat converter code was thrown first.

The mixture control code hasn’t come back yet with just one short drive, but I believe it will show tomorrow during further drives unfortunately.

I guess the next step is ensuring it’s the oxygen sensor and researching if I’d need upstream, downstream, or both.

[Saif2018]

Originally Posted by tej98

Yeah, I also noticed the lpfp pressure is low towards the end of the pull but not really during the cruising logs which is when the code is thrown.

So the original code present was for the mixture control. After clearing codes and resetting adaptations I noticed that the typical cat conversion codes (that are usually present in our tuned cars as shadow codes with MHD) were only present for bank 2 so far. Usually both bank 1 and 2 appear at the same time as the oxygen sensor monitor sets, but bank 1 appears to be lagging a bit now. This leads me to believe that bank 1 oxygen sensors may be lagging compared to bank 2, which is why the bank 2 cat converter code was thrown first.

The mixture control code hasn’t come back yet with just one short drive, but I believe it will show tomorrow during further drives unfortunately.

I guess the next step is ensuring it’s the oxygen sensor and researching if I’d need upstream, downstream, or both.

29E0 is usually either caused by O2 sensors or Injectors.

You could swap the injectors between bank 1 and 2 to see if it makes a difference, its probably the 02 sensors in my opinion.

[tej98]

Originally Posted by Saif2018

29E0 is usually either caused by O2 sensors or Injectors.

You could swap the injectors between bank 1 and 2 to see if it makes a difference, its probably the 02 sensors in my opinion.

Thanks! Which oxygen sensor do you recommend I go after first, the upstream or downstream?

[Saif2018]

Originally Posted by tej98

Thanks! Which oxygen sensor do you recommend I go after first, the upstream or downstream?

Not sure which one, but it's probably best to change them both.

[tej98]

Originally Posted by Saif2018

Not sure which one, but it's probably best to change them both.

Thanks, I think it makes sense to replace both sensors on bank 1 first. I may do the upstream first and then downstream. Honestly at 106.5k miles it’s also just good maintenance at this point even if it doesn’t solve my issue.

[riczon.335i]

Originally Posted by tej98

Hello, I've been getting code 29E0 during cruising conditions which I see is indicative of bank 1 running lean. Bank 1 has all index 12 injectors that I bought used back in October (with ~38k miles on them) to replace my old leaky set on that bank. They have been fine since then and I recently checked the plugs again and found no fuel on them so I know they are not leaking (I assume they could fail the other way and not flow correctly however). This code just started a few days ago as well. Below are logs at idle, a 3rd gear, and a cruising log.


The car is a 2009 335i 6MT running MHD v9 Stage 2 with the supporting mods. All the vacuum lines, TMAP, spark plugs (NGK 1 step colder at 0.022"), charge pipe, and VRSF 7.5" intercooler have under 10k miles on them.


My observations are that idle STFTs are fine, but bank 1 LTFTs are high at ~22%. Under the 3rd gear log LTFTs are near 0 (which I believe is normal) but STFTs on bank 1 begin trending upward, but do not near the limit of 34%. Another note is that my LPFP is showing weakness towards the end of this log, but it does not make sense that this would impact only bank 1 (atleast I think). The cruising log is interesting as bank 1 STFTs do not go above roughly 13%, but bank 1 LTFTs are once again ~10% higher than bank 2.


I have no idea how old the oxygen sensors are but the car does have 106.5k miles on it. Does it make sense to change the upstream sensors or are these symptoms indicative of other issues?


Idle Log: https://datazap.me/u/tej98/idle?log=...18-19-21-22-23

3rd Gear Log: https://datazap.me/u/tej98/mhd-v9-st...18-19-21-22-23

Cruise Log: https://datazap.me/u/tej98/cruise-1?...ta=18-19-22-23


Thanks in advance!

I have been through this before, I had swapped to index 12s thinking it could be injectors but that didn't cure the issue, installed new O2 sensors and that did the trick.

[tej98]

Originally Posted by riczon.335i

I have been through this before, I had swapped to index 12s thinking it could be injectors but that didn't cure the issue, installed new O2 sensors and that did the trick.

Thanks! Did you swap both upstream and downstream sensors?

[riczon.335i]

Originally Posted by tej98

Thanks! Did you swap both upstream and downstream sensors?

I had time to do all four because I didn't want to go under the car to do the work a second time since the downstream ones were a PITA for me lol.

[tej98]

Originally Posted by riczon.335i

I had time to do all four because I didn't want to go under the car to do the work a second time since the downstream ones were a PITA for me lol.

Makes sense, probably good maintenance at this point as well.

[tej98]

I had a bit more time to dig in to diagnosing this and found something interesting with the oxygen sensor voltages. I’m not entirely sure how to interpret these, but should the post cat sensors ever show 0 volts like mine are in the video below?

[tej98]

Wanted to keep this thread updated. I haven't had much time to diagnose but I've still been getting the code on and off over the past couple months, no drive-ability issues whatsoever, and still never a CEL, just a active code that gets triggered (shadow code).

I changed the oil the other day and stuck a boroscope camera up near the O2 sensors and found that the upstream bank 1 sensor appears to be cracked, causing an exhaust leak. This gave me more confidence to just order both bank 1 and 2 upstream O2s. I'll update once I have them installed as well as inspect the old cracked sensor when I remove it in a couple weeks.

I've never seen a cracked oxygen sensor so this is a first for me. A quick google search also doesn't show much about cracked O2s on any platform, let alone the N54.

[tej98]

Finally swapped out both upstream sensors and cleared both oxygen sensor adaptations in MHD but seem to have the same trim issue on bank 1. Code has not returned yet, but I suspect it will.

[Wolf 335]

Originally Posted by tej98

Finally swapped out both upstream sensors and cleared both oxygen sensor adaptations in MHD but seem to have the same trim issue on bank 1. Code has not returned yet, but I suspect it will.

Thanks for the update. Usually the ecu needs to register a few driving cycles before the code pops up.

What’s next, downstream O2 sensors?

[tej98]

Originally Posted by Wolf 335

Thanks for the update. Usually the ecu needs to register a few driving cycles before the code pops up.

What’s next, downstream O2 sensors?

I suppose I could do those. If I did them, they would be the ones that I could wire in (generic Bosch ones) since they may not be bad at all. After watching voltage switching for a while I do think they are working fine though.

What may be worth a shot is swapping an injector from bank 1 to bank 2 one at a time and seeing if a difference is made. But to be honest, I have never gotten an actual CEL for this, only a shadow code.

Before more diagnosis I may just wait until the car throws an actual limp mode with CEL. It also may be worth waiting to replace the downstream O2s until I actually get a code for them. The fact that the car drives perfectly fine under cruise or boost, and that it has great cold and warm starts has me hesitant to throw more parts at a perfectly running car. From logs it does need an LPFP so I'll order one soon, but that shouldn't impact this issue (one bank only).

Thoughts?

[tej98]

Tried out a 91oct tune after noting some minor timing corrections on the 93oct tune (I don't need maximum power anyways). Still running 93 fuel with the 91 tune though. Interesting to note that fuel trims in general have decreased, but the variance between bank 1 and bank 2 is still there by roughly 10%.

https://datazap.me/u/tej98/mhd-v10-s...ata=3-23-24-25

[tej98]

Well it’s been roughly 2300 miles since the O2 sensor install and adaptation reset. So far the code hasn’t returned, but fuel trims on bank 1 are higher than bank 2. This was all types of driving from some mountain drives to a 1200 mile road trip of long highway cruising, and even heavy city traffic.

I’m still skeptical about this, but I’ll keep the thread updated if the code comes back.

[Maxmil982]

Second tune light do it

[tej98]

Originally Posted by Maxmil982

Second tune light do it

I actually ended up flashing back to the 93oct v10 Stage 2 tune after seeing the same trim behavior as well. Over 2000 of the miles were logged with this flash.