Hi all,

I'm battling an intermittent 29E1 code on a 2010 535i with 92k miles. There's also a very subtle hesitant idle, particularly when cold. As I understand it, it's triggered by the O2 sensors when the bank runs too lean.

Within the past ~10k, I've replaced the plugs/coils and then all 4 O2 sensors.

I recently learned that injectors can be swapped without too much trouble (and I have a working INPA to do the appropriate coding), so my next troubleshooting step is to swap injectors from bank 1 to bank 2 and vice versa. If the code follows, I know I'll need new injectors (as there's a chance they're the originals).

Any reference to this code I've seen in concert with 29E0, in which case it's likely upstream from the turbos (MAF, etc.), but for an individual bank it could be anything from an air leak in the exhaust manifold, a turbo on its way out, a bad cat, carbon buildup, etc. Anyone with experience with these codes or who thinks I'm overlooking something?

Thanks for any input!!!!

 

My car(2010 535) got out of the shop yesterday with three codes, 29E1 and 2E81 and 2E82. My 3rd party warranty said my water pump was toasted (2E81 and 2E82), and that the 29E1 was also a water pump error code. Didn't make too much sense to either myself or my Indy. We just accepted the reply since they paid for the water pump. Now we'll wait and see if that error code comes back.


A couple weeks ago I strayed away from Shell and went to a Mobil gas station and put in 93 octane, same gas went into my Audi on the same day. Five days later is when the BMW first threw the 29E1 code and my Audi threw a similar code. Could be coincidence but thought I would let it out.

 

Thanks for that - actually the water pump recently gave out on this car so the pump + thermostat were replaced. The issue existed before/after so pretty sure its unrelated.

The code's been coming up over the past year or so so doubt it's due to fuel either...

 

If you double checked and made sure the O2 sensors were in the right place (downstream has right sensor), checked for exhaust leak, checked the injectors then you should check your HPFP. It can also be a reason you get the code.

I am betting it is the injectors though. You should find the problem switching them out.

 

Wanted to update the thread in case someone finds this in a search.

The car (2010 535i) had a rough idle, felt like it was misfiring under acceleration, and throwing the following codes:

29E1 - fuel mixture control bank 2
29CF - misfire cyl 3
29D0 - misfire cyl 4
29CC - misfire multiple cyls

I went ahead and swapped injectors from bank 1 to bank 2 and vice versa. After driving a bit the misfire got worse, intense shaking and the following codes:

29E0 - fuel mixture control bank 1
29CD - misfire cyl 1
29CF - misfire cyl 3
29D2 - misfire cyl 6
29CC - misfire multiple cyls
30FF - low inlet manifold pressure
2C77 - lambda probe after cat conv signal full load


Since at least two misfire codes followed the way I swapped injectors (cyl 3 -> 6, cyl 4 -> 1), I figured it was safe enough to invest in some new injectors. Swapped them out and car is good as new.


Thanks again to who replied with possible ideas/advice.

 

Thanks for updating. I have been battling the lean fuel mixture codes for about a year. I also have the cold idle hesitation.

BMW wouldn't do anything about it because it passed all their tests after they reset the codes. It would pop up again in about 3 days. Now I'm out of warranty and have to find an indy to fix. This helps me head in the right direction.

 

I got my local dealership (Mountain View) to price match Silver Spring (getbmwparts.com) @ $227 a piece if it helps.

Sometimes complete sets advertised as good working condition come up on eBay for several hundred, may have gone that route if I wasn't pressed for time.

 

If you had your car looked at for the same reason under warranty and still have the issue without warranty the dealership will still cover it. It was an existing issue that they could not diagnose because they did not want to cover it. Take your receipts and have it looked at again. Once they find it pull the receipts out and say this was an existing issue that never got resolved and they will cover it. Do no bring up the past until they acknowledge there is something wrong because if you do they will tell you the same thing to avoid fixing under warranty. I have done it multiple times at BMW and Honda.