my '01 clk430 recently decided to start only when it feels like it. when i turn the key to start the car the entire dash lights up and the starter seems to turn but the engine won't kick in. when i turn the key to position #1 the 'check engine' light remains lit. the owners manual (yes, i actually read it!) tells me the gas gap might be the culprit. i checked the cap and it seems tight, so i removed it and replaced it. 3 or 4 tries later the car starts. i've duplicated this sequence 3 times now. is the gas cap trick a coincidence? the flange and gasket seem to seal properly. what gives?

in case it matters, the car has 58k miles on it and has not had any service recently. the problem occurs mostly when the engine is cold.

(note: this is a duplicate of a post in the general tech forum.)

 

I know the clk's have problems with the crankshaft position sensor but the check engine light would not turn on.