Originally Posted by
jgreen
As of last week the dealer advised to change out the engine harness.
Typical trouble shooting advice from a dealer - If you keep going to a dealer, this kind of asinine advice is all you are going to get.
It is apparent that you are willing and able to deal with this yourself, why bother with going to someone who knows next to NOTHING about your car?
the temp sensor is not giving errors so they are not replacing it.
MORE foolish advice. The sensor can produce inaccurate readings, BUT provided they are within the defined range, there will be no code.
And it works both ways - my car was throwing O2 sensor codes as well as misfire codes. I changed all plugs and plug wires, but not the O2 sensors - this stopped ALL codes. My misfire codes were due to real misfires and my O2 sensors were reporting out of range oxygen levels NOT because they were defective, but because they DID see REAL oxygen levels that were too high because the misfires meant there was too much oxygen in the exhaust.
A DTC code for any item does NOT automatically mean that item is defective, it may be that it is reporting abnormal readings because that is precisely what is happening.
I think you'd be no worse off chasing this yourself (maybe with some help from us) than running back to the damn dealer. If you need experienced, professional help, take the car to some local shop that is KNOWN for Mercedes experience. Anyone who has chased similar issues in an SLK320 or one of it's cousins will likely already suspect what is going on, as he has seen it before.