chatham

2012 C250

had multiple warning lights come on. EPS, ABS, EPS off, and engine light. pull a C0034 code that indicated that right front speed sensor was bad. replaced that sensor but I cannot clear the code in the vehicle. I can clear diagnostic codes but not pending codes, so the C0034 code is still there and the warning lights all remain lit. additionally the Attention Asst is inoperable. any ideas?

Estlander

Old thread, I know, but I have the exact same problem with my 2012 C250. Replaced the part, but can't erase the code and the warning lights to go off.. The old speed sensor definitely was dead as I couldn't get any reading from it with an Ohmmeter. The new part reads out fine.

chatham

you MUST use official Mercedes parts. i tried after market parts and had the same problem. I found out that Mercedes CPU's are very sensitive to getting the correct readings. Probably programmed that way to use only OEM parts. After i switched to Mercedes parts the code and warning light will go away. just do a search for the part no. and make sure they are OEM parts. about two months later the other side went out, used OEM and no issues.

Estlander

I did replace it with an OEM part. So the lights are supposed to go out by themselves once the part has been replaced and no need for some Mercedes specific code reader to erase the codes?
I read somewhere that ABS codes do not go away by themselves, not even by removing the battery terminals.

chatham

as i recall the code should clear it self. it might take a day or two for the cpu to relearn.