[savannahz]

I've gotten a shadow code of 2c7f a few times and the other day it manifested into a check engine light on the dash. I have two questions (I'm catless dp's and mhd 7 2+)(reset lambda via mhd):

1. the code reads: Lambda probe behind catalytic converter 2, trimming control
which sensor is this exactly? is it one of the two plugged into my catless downpipes? If so, is it the black or grey one? From searching, it appears it's the rear bank?

2. I'm increasingly having issues with what feel like mini misfires, or very slight hesitation, noticed especially while I'm idling and when I have the cruise control on. Last night I had a couple hundred mile drive and the car was at 2300rpm, on cruise, and it was just very slightly jerking a good bit of the drive. Power is not an issue during the rev band....it's just when idling or trying to hold a particular rpm. Could this be due to the O2 sensor trimming going bad? I've recently replaced spark plugs (this happened before those as well) and did a valve cleaning 20k ago. Plugs looked good and nothing obvious concerning a leaking injector showed.

Thanks!

[Nexus313]

Bank 2 O2 sensor plugged into the downpipe itself showing a bad reading.

O2s are a huge mess on these cars - especially when you go catless downpipes..

Having similar symptoms as you on my thread: http://www.e90post.com/forums/showthread.php?t=1426553

Hasn't been solved for 1+ month now.

[bravehart38]

Had a similar issue. Was getting a 2C32 (trimming error)cat code. Eventually had to replace both the pre and post cat O2 sensors to resolve it.