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 R350 Engine Performance Problems Due to Crankshaft Position Sensor Failure
Mercedes-Benz R350 Problem
Average Mileage: 70,333 mi (28,000 mi - 106,000 mi)
The engine will crank—but not start
Visitor, 2006 Mercedes-Benz R350, 106,000 mi
Same problem engine check light, manyfacture problem with Camshaft Adjuster Solenid Failure.
Is MB going to recall
Check engine light problem in starting and stop some times.