Help.. Error codes not going away!

[Snappa2000]

Hi all,

Firstly I have a 2012 E92 M3 with an Akrapovic Evo exhaust including the Delete-R module for the primary cat removal in the Akra. I have been getting some weird errors over the last few months from getting none before. The car is a weekend driver so initially the battery was suspect, so this has been replaced. Other errors showed the Pre-Cat heater on bank 2 O2 Sensor. This has been replaced with a new Bosch one.

It has now settled on the same faults now, and am seeking help to work out what is going on. Using Carly for BMW, I have read the codes. The car runs fine, but throws the CEL on the dash. I reset the codes and they end up coming back

The below two codes pop up:

2741 Lambda probe heating controller diagnosis before Kat Bank 2
274F Lambda probe error Nernstleitung before Kat Bank 2

Any recommendations would be welcome.

Thanks

[deansbimmer]

Looks to be a fairly common sensor malfunction. Sometimes these cars are finicky with using aftermarket parts house sensors. If you replaced the driver side pre-cat sensor, I would suggest a genuine BMW unit instead. Or if you want to try swapping the sensor from bank 1 which seems to be happy, you can rule out the issue being a sensor.

[Snappa2000]

Hi,
The part that was replaced has the same part number on it as it was originally a Bosch unit. I originally did swap them over which is when I had other errors pop up and that bank sensor was failing.
I’m thinking it’s either a problem with the wiring to the DME or the DME itself!
Would be good to have an actual fault description for the code.
Thanks for suggesting the swap.
Cheers

[Snappa2000]

So the plot thickens.... I have pulled out the DME and checked the resistance from the 44Pin connector (Pin23 - Bank 2 PreCat) to the fuse point (J11 i think - the 20A fuse for the heater circuit behind the glove box).

This shows the full wire path from DME to the Power feed.
This measured 4.5 ohm.
I also measured Pin1 (Bank 1 PreCat) and this measured 4.2 ohm.

Some more questions have cropped up.

1. Can this be the DME as everything else is fine?? But its random, if it was the DME it would continuously fail.

2. Could it still be a faulty O2 (recently replaced with the proper Bosch one for the M3). Is there something that is killing it. Again if it was faulty it is not consistent. Could the O2 be failing the resistance at higher temperature?

3. Could it be the short runs and not the build up of carbon??

4. Could a tune fix this issue.

Hmmm, thanks

[deansbimmer]

Since this is a bank specific issue, did you try swapping the sensors from the faulty bank to the error-free bank as suggested? This is the far easier trial than trying to diagnose a DME.

[joe6mt]

You will need a Tune to get rid of the Cel on the dash. your Akra Evo doe not have primary cat, increase emission. Delete-R module hit or miss.

[Snappa2000]

Originally Posted by deansbimmer

Since this is a bank specific issue, did you try swapping the sensors from the faulty bank to the error-free bank as suggested? This is the far easier trial than trying to diagnose a DME.

Yeah I did this first and the banks was still #2

[Snappa2000]

Originally Posted by joe6mt

You will need a Tune to get rid of the Cel on the dash. your Akra Evo doe not have primary cat, increase emission. Delete-R module hit or miss.

So i get the retune deleting the primary cats. Does a tune also adjust the heater readings from the precat?
Could an increase in emissions cause issues with the O2 and case premature failure?

Thanks

[joe6mt]

Correct. I had BPM tune took care of the rest. Shoot mike a Pm.

[BPMSport]

We can certainly mask those faults, but not recommended. First suggestion would be to switch the sensors from one bank to the other and see if the fault moves. If it doesn't move, then it's likely not the sensor itself, and more likely the wiring, or a faulty DME (which would be unlikely). Hope this helps!

[Snappa2000]

I have previously swapped them and have since bought a new bank 2 pre-cat sensor. I’ll find some time to swap these again.
I have validated the wiring as above so don’t believe it’s a problem. I am hoping the DME issue is very rare.
Just calling it out. COULD it be related to short start stop where condensation occurs in the exhaust and may affect the heater element?? As when I drove it as the daily driver the other week it didn’t report a fault!
Could it be possible that a leaky injector may cause O2 issue further down during startup?
This is starting to do my head in.
Thanks for everyone providing some info to try, mich appreciated

[TWiTCHY]

Sorry to revive this - Snappa2000 , did replacing with a new sensor fix your issue? I have the same issue but Bank 1. Been on Stage 2 Alpine tune for a while now, but not sure if it's related.

[Snappa2000]

I have found a couple of things that had helped me. Firstly I start my car a little different now. I put the keys on in and then put my belt on before I start it. Funny as it sounds it lets the fuel line prime properly. I also wait for my cold start to calm down before I drive off. The other thing I did was clear my adaptions for my Lamba sensors (there was two adaptions that were cleared).

Since doing these I have not had the CEL show!!

Until the other morning on the start of our MClub breakfast run where I started the car and left straightaway. So didn’t wait for the cold start to calm down and then it appeared.

After three start stops of that motor and 100kms later the light went out by itself

I think it’s related to the primary cats missing due to the akrapovic exhaust and the way the car is. Still performs well and no major issues now

[MPower7]

Hi guys, same exact issue here. I have test pipes and a tune that codes out the primary cats. I just cleared the adaptations and the codes. Are these sensors necessary if the primary cats are coded out for proper engine function? Thanks!

[Snappa2000]

No sure if you can code out the specific sensor codes, but I believe the sensors are still required.

I am still getting the two errors which is starting to really bug me now.

Has anyone else had the same/similar issues and got a full scan check through BMW to determine what it was..

Or should i book her in?

[deansbimmer]

Wait, it has been 6 months and you still haven't had anyone run diagnostics on it??

[Snappa2000]

6 months may of passed but only 500km have been added to the clock. It’s not my daily driver

[Snappa2000]

UPDATE:
Hopefully this will not jinx me, but I believe I have found the root cause of most 'weird' lambda/O2 sensor errors.

Some history, I had a 'Kia' Bosch sensor on Bank 1 (Don’t ask it was there when I bought the car) and the proper M3 Bosch sensor on Bank 2 (the one with the error). I had faults appear and then thought it was a simple replacement of the sensor, so bought a new one.

The Kia O2 never gave me any faults, I have for the last two plus years tried to work through this error. The Kia one is the same spec sensor, but the length of the cable is slight shorter.

Over the weekend I had the car up on the hoist and decided to move the original (faulting) sensor to bank 2 and replace the 'Kia' one with the original sensor that I previously replaced for a new sensor back into Bank 2.

I first thought that there must be a poor connection on the pin for the heater as I could never believe I could be killing these sensors due to having an exhaust fitted. Not to mention checking the cables and everything from the ECU to the fuse box.

After removal, I noticed that the 'Kia' sensor was difficult to remove, I then looked at the connectors of the Bosch sensors in case they were corroded or damaged causing a poor connection.

I was surprised to find that the 'Kia' sensor pins were almost 2.5x wider that the correct Bosch sensor, and definitely 2x thicker than M3 Bosch sensor! This started to make sense that the M3 sensors are not making or losing contact.

I then decided to bend the pins inwards slightly to force a connection. I checked the fault again in the ECU and it was there but not active! I cleared the error and checked again, and still good.

The two sensors have been in for the last 150km, and the car has been started and stopped 10 times since and NO ERRORS!

Note: This may not be your issue, I would still validate the heater resistance etc. but for a quick fix, it may just help.

Also side note, the car is performing very nice to, which may also have to do with the contact issue.

Hope this helps a few people, and Bosch may need to reassess their pins!!

Cheers

[MikeYQM]

Originally Posted by Snappa2000

UPDATE:
Hopefully this will not jinx me, but I believe I have found the root cause of most 'weird' lambda/O2 sensor errors.

Some history, I had a 'Kia' Bosch sensor on Bank 1 (Don’t ask it was there when I bought the car) and the proper M3 Bosch sensor on Bank 2 (the one with the error). I had faults appear and then thought it was a simple replacement of the sensor, so bought a new one.

The Kia O2 never gave me any faults, I have for the last two plus years tried to work through this error. The Kia one is the same spec sensor, but the length of the cable is slight shorter.

Over the weekend I had the car up on the hoist and decided to move the original (faulting) sensor to bank 2 and replace the 'Kia' one with the original sensor that I previously replaced for a new sensor back into Bank 2.

I first thought that there must be a poor connection on the pin for the heater as I could never believe I could be killing these sensors due to having an exhaust fitted. Not to mention checking the cables and everything from the ECU to the fuse box.

After removal, I noticed that the 'Kia' sensor was difficult to remove, I then looked at the connectors of the Bosch sensors in case they were corroded or damaged causing a poor connection.

I was surprised to find that the 'Kia' sensor pins were almost 2.5x wider that the correct Bosch sensor, and definitely 2x thicker than M3 Bosch sensor! This started to make sense that the M3 sensors are not making or losing contact.

I then decided to bend the pins inwards slightly to force a connection. I checked the fault again in the ECU and it was there but not active! I cleared the error and checked again, and still good.

The two sensors have been in for the last 150km, and the car has been started and stopped 10 times since and NO ERRORS!

Note: This may not be your issue, I would still validate the heater resistance etc. but for a quick fix, it may just help.

Also side note, the car is performing very nice to, which may also have to do with the contact issue.

Hope this helps a few people, and Bosch may need to reassess their pins!!

Cheers

Did the “bending the pins” fix continue to solve the problem long term? Has the “Kia” O2 worked long term? Any chance you have a part number for the “Kia” sensor?

[Snappa2000]

Longer term update:
I have been running the car with the bent pins to get a better connection and have not had the error pop up since! I have had a BPM Tune put on since then but nothjing special from Mike on that, and the sensors and codes are still enabled.

Car runs really good and i have to say the O2 sensor must of been miss reporting as it definately runs better since that.

As with an other sensor and plug, inspect it and dont assume all is good, make sure a good connection is made beofre changing and spending money.

This sort of adds up to those that have had exhaust changes and the O2 sensors are unplugged and plugged in, which may loosen up the connectors as the connector pins are thin.

Again, hope this has helped.

Cheers