2007 Mercedes-Benz C-Class - crank but won’t start after a drive

I own a 2007 C-230 with 140 thousand miles, very clean, meticulously serviced. When driven non stop lets say 100 miles, Turn off, it will then crank but not start. Let sit for several hours or over night then it will crank and start. MB says they can not fix what ain’t broke. HELP

I presume it always starts fine for them at the shop. This is a common problem for car owners, car won’t misbehave at the shop. Shop balks at fixing this sort of problem b/c it may take many hours of effort, only to discover a wire has come loose. Then customer complains about the $750 invoice to tighten the wire connection. I expect that’s what’s going on.

If I had that problem myself, I’d consider these two option

  • Ask shop to keep car, provide you a lender (which you may have to pay a daily fee for), and one of their shop techs drives your car as their daily driver. Eventually it will fail, and shop tech will then be able to figure out why.

  • Replace crank position sensor on a flier. That part has a known failure mode when hot. Symptom is what you report, cranks ok but won’t start when engine hot. Not just on your car, but many makes/models. This failure often doesn’t produce a diagnostic code.