I have just replaced both engine mounts and the car runs almost as smooth as it did when I bought it!! :-)
I still have a check engine light, I will check the codes and post them.. The good news is that the terrible rough idle is gone due to new engine mounts, and replacing them was not that hard to do. They were totally shot!!

 

My Mercedes is 2004 C230 Kompressor. It's been maintained along the time I have owned it, but this year is the first time my check engine light has come on. I searched threads and found one suggestion which may save people a lot of money.... go to an auto parts store - AutoZone was good for me.. tell the counter guy your check engine light went on and you need a part but not sure which one... ask him if he has an OBD2 scanner.. if they're good - they will have one and check (scan) your car for free.. it will give you the Code no. for the problem... I saved over $100 where the atuo repair shop nearby wanted to put the car on the 'diagnostics' machine... the auto zone employee told me the problem. As it turns out it could have been something as simple as the gas cap not on tight, spark plugs, plug wire, thermostat or more involved.. valves or something with the head... my fuel was lean.. and (bad me), I have been saving money by buying 87 unleaded gas versus the 93 high test- recommended by the manual. He suggested I run out the gas and go back to 93. He erased the check light off my panel (thru his machine) and said come back if it comes back on again and they'll reassess! Thank you AutoZone.. I will be back.

 

a week ago I had a total of 4 error codes, P0105, P0170, P0173 and Pending P0400
I did more digging around under the hood and found the vacuum line to the MAP Sensor was dry rotted off, it was not even connected to the sensor anymore. I repaired the line and cleared the codes, drove it 100miles with several start and stops, the codes have not come back and I just had it smogged yesterday and it passed with flying colors!! Whew!!:-)

 

p0455 code ?