Cel: 27c6 2726 277c 2770

Kwike92M3 · 10-26-2017, 02:25 PM

Posting this to hopefully help anyone who runs into this problem!
My check engine light came on a while back, I cleared codes and nothing returned. Eventually the CEL returned multiple times in a faster recurring time frame. There were no driveability concerns, no change in accel/idle/etc.
Can't really comment on fuel mileage because I drive the car somewhat spirited at any chance I get the opportunity to.

I am using an OTC Evolve diagnostic tool running the Bosch 3.0 Software for diagnostic.

The codes retrieved at this time were:
277C Lambda sensor diag trim control bank 1 not detected
27C6 Lambda sensor AD diag trim control bank 1 below min threshold
2726 Lambda sensor plausibility VKAT bank1 not detected bank 1
277D Lambda sensor diag trim control bank 2 not detected
Again, for reference and repair info, bank 1 is passenger side (cylinders 1-4).
My vehicle is a 2013 e92 M3 with competition package. DCT trans. 42k miles.

The codes are indicating erratic readings from the Lambda sensors on both banks, and fuel trims are reading all over the place (positive and negative values). Nothing was making sense.
I first opted to smoke test the intake due to both banks being effected by the fault condition. I also tested the secondary air injection check valve to make sure there were no issues there, even though there wasn't a fault code stored. No issues were found @ this time.
For everyone's reference, THIS VEHICLE DOES NOT HAVE A CONVENTIONAL MASS AIR FLOW SENSOR. The car calculates its fuel/air mixture based off a MAP sensor.
I next moved to the exhaust and removed the muffler. I blocked off one side of the exposed exhaust tubing, and made an adapter for my smoke machine to charge the exhaust system with smoke. I found bank 1 exhaust flange leaking @ the flange connecting to the cat, right before the lambda sensor.
I replaced both sides exhaust flange gaskets with new hardware, and no issues have returned. I was pretty sure I had an exhaust leak as it sounded like it when I would drive next to a retaining wall or a barrier, but am pretty unfamiliar with this platform and chalked it up to the magical noises of an M3. I was wrong haha

I hope this helps anyone in the future who runs into this issue.

I would also like to mention that I found a TSB stating that a few M3s escaped the factory with the Lambda sensor harness was installed on the reverse side (right on left, left on right). It is a very simple process to check. The right hand side harness is labeled with a sticker that has an "R" on it. It is very simple to see. If the "R" is on the left side, this may be the problem.

Good luck guys!

-TM

10-26-2017, 02:25 PM	#1
Kwike92M3 Private First Class 75 Rep 146 Posts Drives: 2011 E92 M3 Supercharged Join Date: Aug 2014 Location: Dallas iTrader: (2)	Cel: 27c6 2726 277c 2770 Posting this to hopefully help anyone who runs into this problem! My check engine light came on a while back, I cleared codes and nothing returned. Eventually the CEL returned multiple times in a faster recurring time frame. There were no driveability concerns, no change in accel/idle/etc. Can't really comment on fuel mileage because I drive the car somewhat spirited at any chance I get the opportunity to. I am using an OTC Evolve diagnostic tool running the Bosch 3.0 Software for diagnostic. The codes retrieved at this time were: 277C Lambda sensor diag trim control bank 1 not detected 27C6 Lambda sensor AD diag trim control bank 1 below min threshold 2726 Lambda sensor plausibility VKAT bank1 not detected bank 1 277D Lambda sensor diag trim control bank 2 not detected Again, for reference and repair info, bank 1 is passenger side (cylinders 1-4). My vehicle is a 2013 e92 M3 with competition package. DCT trans. 42k miles. The codes are indicating erratic readings from the Lambda sensors on both banks, and fuel trims are reading all over the place (positive and negative values). Nothing was making sense. I first opted to smoke test the intake due to both banks being effected by the fault condition. I also tested the secondary air injection check valve to make sure there were no issues there, even though there wasn't a fault code stored. No issues were found @ this time. For everyone's reference, THIS VEHICLE DOES NOT HAVE A CONVENTIONAL MASS AIR FLOW SENSOR. The car calculates its fuel/air mixture based off a MAP sensor. I next moved to the exhaust and removed the muffler. I blocked off one side of the exposed exhaust tubing, and made an adapter for my smoke machine to charge the exhaust system with smoke. I found bank 1 exhaust flange leaking @ the flange connecting to the cat, right before the lambda sensor. I replaced both sides exhaust flange gaskets with new hardware, and no issues have returned. I was pretty sure I had an exhaust leak as it sounded like it when I would drive next to a retaining wall or a barrier, but am pretty unfamiliar with this platform and chalked it up to the magical noises of an M3. I was wrong haha I hope this helps anyone in the future who runs into this issue. I would also like to mention that I found a TSB stating that a few M3s escaped the factory with the Lambda sensor harness was installed on the reverse side (right on left, left on right). It is a very simple process to check. The right hand side harness is labeled with a sticker that has an "R" on it. It is very simple to see. If the "R" is on the left side, this may be the problem. Good luck guys! -TM
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