HELP!!! I have a 2000 S500 that will start, but then will rev and stay surging at 4400 rpm. (I have heard that this is a safety feature to prevent the engine from over revving.) If I disconnect the MAF, it will run up to redline, at which point I turn off the key. I have replaced the MAF but that didn't help. (I focused on the MAF because of other posts suggestions) Do I need to somehow reset the computer after replacing the MAF, or is there another problem. I read somewhere that an O2 sensor may cause this problem. I am very far from a Mercedes shop, (Not to mention not rich enough to take the car to one) Does anyone have any suggestions on what I can do?

 

Possible Idle Control Valve fault or ECU would also spring to mind. You need to get it hooked up to a STAR machine to read the error codes.

No disrespect, but if this is the case then don't buy an w220 S500, they can be expensive to run and maintain, especially the early w220 years.