The crankshaft position sensor may fail. Symptoms of this are: The engine will crank—but not start—especially when the engine is warm. The car may start again if it is left to cool off, but it may run roughly or have poor performance. Communicating these specific symptoms to your technician can save diagnostic time.Google+
Car Problem Reports
Mercedes-Benz C320 4MATIC Engine Performance Problems Due to Crankshaft Position Sensor Failure
Mercedes-Benz C320 4MATIC Problem
Average Mileage: 131,500 mi (110,000 mi - 154,000 mi)
Visitor, 2005 Mercedes-Benz C320 4MATIC, 122,000 mi
Car totally died while idling in grocery store parking lot. Would not restart. Military Veteran (go Vets!) helped get my car into neutral (using switch inside cup holder) and push it into empty parking space. Three hours later, after being towed to closest Merc Benz dealer, and $100 for taxi cab ride home (with my German Shepherd in the back seat of the taxi with me), I was totally drained. According to two separate dealerships, this is one of the two most common problems w/the 2005 C class - the other being the fuel pump suddenly stops. I spent $1500 to have the fuel pump replaced proactively - didn't want to end up on the side of the road again.
Visitor, 2004 Mercedes-Benz C320 4MATIC, 140,000 mi
Car would crank but fail to turn over when car was warm. If left to cool, car would start but stall as it warmed up. Replacing the crankshaft position sensor (~$500.00 excluding the tow) solved the problem.
Visitor, 2005 Mercedes-Benz C320 4MATIC, 154,000 mi
crankshaft sensor bad -check engine light on, diagnosed by mechanic. Replacedd
Visitor, 2004 Mercedes-Benz C320 4MATIC, 110,000 mi
cranks, but engine will not start. changed inition& crank censors. still having problem.