What are the symtoms and error code when this occurs. Just curious for future reference.
From my experience:
Initially,the engine stalled without warning. I pulled off to the side, turned off ignition, waited a few minutes and restarted the vehicle. Engine restarted and car ran fine except CEL warning light showed up. It was late in the evening, so I just turned off the engine after parking in home garage. Next morning, the engine started fine and CEL warning light disappeared. Talked to MB service advisor and he recommended observation as the CEL light went away.
A week later, while getting on the the off-ramp from freeway, engine stalled with our warning. I was able to cruise and get into the "emergency" lane at the side of the off-ramp. This time turning off the ignition and restarting did nothing. Engine would crank and nothing else would happen. Had to MB roadside assistance and they sent flat bed tow truck and got it into MB shop in mid-evening.
Next morning, service advisor said the Crankshaft Position Sensor was "toast", i.e., non-functional.
Vehicle had 64,187 miles, and one month shy of 6 years of ownership from new, single driver.
From the Invoice: "Engine test with DAS, code P2034-008. Test individual components per Diagnostic Trouble Code (DTC), crankshaft position sensor failed resistance test (56 MegaOhms MΩ when heat is applied). Replaced crankshaft position sensor, reset rotor adaptation and test drove car."
Currently the 2008 SLK55 has 87,610 miles, and 8.5 years of ownership from new, single driver, used almost daily.