benwaide

I have a Check Engine light on my 2007 CLK350 that shows as code P0177. O2 problem? No discernible performance problems. Any suggestions?

Rudeney

Arer you sure it's P0177? I am not finding a cross reference for that generic OBDII code to the DTCs for ME 9.7

benwaide

The code reader actually read P2177 but the instruction book led me to believe I should drop the 2.

Rudeney

I can't find a cross-reference from that generic OBDII "P" code to an MBZ DTC. I do find DTC 2177, which is "2177 The power supply at the input of the engine control unit has a sporadic malfunction. "

benwaide

I found another explanation for that code at Actron on-line. Not sure if it is correct for MBZ. "system too lean off idle bank 1". Not sure what that means either. Car seems to be running fine.

Rudeney

If you clear the code, does the MIL illuminate again?

benwaide

Yes, it does.

Rudeney

OK, that might correlate to these DTCs:

2089 The mixture in the right cylinder bank is too lean in the partial load range.
2091 The mixture in the right cylinder bank is too lean when idling.

Both of these suggest a problem with the pressure sensor (B28):

benwaide

Thanks, Rodney. I changed the air filters and cleared the code and this time it did not re-appear! Not sure if I jarred something as I changed the air filters or what but as of right now I am clear.