Originally Posted by
Mrmiata
I'm going to guess your "but nothing" means the starter spun but the engine wouldn't fire. This would be the CPS typically. "Nothing" here is generally accepted as no starter engagement. "If" that happens then your looking at the RCM repair.

Sorry Mrmiata i meant starter spun but the engine wouldn't fire.
i can't seem to find the Bosch Crank Position Sensor in the UK, but will ring Mercedes tomorrow and see what they have.