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 R500 Engine Performance Problems Due to Crankshaft Position Sensor Failure
Mercedes-Benz R500 Problem
Average Mileage: 63,885 mi (39,000 mi - 87,655 mi)
Visitor, 2006 Mercedes-Benz R500, 39,000 mi
I had this problem as well. Engine power cut off and steering locked! All I could do was brake. Lucky for me, I had just gotten off the freeway.
When I took my car to the dealer, they also told me they needed to replace my transmission and torque converter assembly, front and lower control arms, and the engine and transmission mounts. My wife drives this car and she is a very good driver. Mercedes has problems!
Visitor, 2006 Mercedes-Benz R500, 87,655 mi
I am still dealing with the car having trouble starting on hot days. Starter keeps turning over but the engine will not crank. After letting it sit for a few minutes then the problem goes away. I can not dupicate the problem in my house or on days when the temperature is below 80F.