HI EVERYONE IM HAVING A PROBLEM WITH MY 03' C320 MOST OF THE TIME IT STARTS BUT SOMETIMES IT DOESNT. SOMETIMES IT STARTS RIGHT UP SOMETIMES IT CRANKS BUT DOESNT START AND SOMETIMES ITSTARTS THEN IMMEDIATELY SHUTS OFF. SO I TOOK IT TO THE DEALERSHIP THEY SAID A CODE FOR THE CRANKSHAFT POSITION SENSOR CAME UP SO THEY REPLACED THE CPS. I PICKED THE CAR UP DROVE IT AROUND FOR A WHILE STOPPING AT STORES AND THE LAST STORE I STOPPED AT WHEN I CAME BACK OUT ABOUT 30 MIN LATER IT CRANKED BUT WOULDNT START THEN IT STARTED BUT TURNED RIGHT OFF .IT ALWAYS AT LEAST CRANKS. I HAD TO LET IT SIT FOR ABOUT 15 MIN THEN IT STARTED UP. SO I TOOK IT BACK TO THE DEALERITS AT THE DEALERSHIP NOW AND IT HAS BEEN FOR THE LAST WEEK AND THEY'RE STILL SAYING THEY DON'T KNOW WHAT THE PROBLEM IS NO CODES ARE COMING UP I DONT KNOW WHAT TO DO .............ANY IDEAS OR HELP WOULD BE APPRECIATED THANKS

 

it could be you need a tune up, maybe replace the spark plugs?

 

have been having the same problem and traced the fault to there being intermittant power to the fuel pump. changed crank sensor but no difference so today changed the rear Sam unit (not cheap at £277 UK pounds) as they cause problems on earlier c classes 2001 (mine) and later. Car seems to run ok now but have lost my fuel gauge. My local independant says this is normal and they should be able to sort it and clear any codes on there Star system.