hi,thanks Richard for you reply,i just want to add some more info ,yesterday i have notice that if the temp.gauge go to approx. 90 Celsius / one oklock on the gauge / and i turn the car off it want start again until cools down, if the temp.gauge go only to 80 Celsius / 12 oklock/ the car will start no problem,any suggestions? should i take the car to mercedes workshop or try replacing the crankshaft position sensor? thank you