Odd Piggy

My daughter asked me for help with her 2004 CLK500, M113 engine, 55,000 miles. The car starts and runs fine, but will intermittently stall when stopped at a stop light. The car restarts on the first try and will not stall again for some time. It is impossible to predict when the stall will occur.

I have had crank position sensor failures on two other MBs with M112 engine variants and one fuel pump failure. Since the car restarts immediately, I think it is unlikely that either of these is the problem.

Can one of the experienced DIYers give me a direction to go? MAF sensor?

Serndipity

I would not rule out the CPS just yet (e.g. very common failure on both the M112/M113).

Mine began failing, at 80,000 miles, with a no start after being parked, until the engine cooled. Also threw a CEL, indicating a CPS fault, which I cleared.

Couple of days later, engine stalled at a traffic light, but was able to quickly restart. The stall, lit up the instrument cluster temporarily, but no CEL thrown.

Since it's only $50 part and a pretty easy DIY (e.g. with a E socket and long extension), didn't wait for a third occurrence and replaced the CPS. No further no starts / stalls since.

Odd Piggy

Thanks for the experience, Serndipity. Different failure symptom than I had experienced -- my ML350 and E320 just went stone cold dead when their sensors failed. I'll order the CPS online and change it at my next opportunity.