Check engine light went on (actually it went on and off a few times in the weeks leading up to my service appointment). Mercedes mechanics say it's the crankcase vent valve needs replacing. Estimate is $3300 to repair including the $1425 part "intake line". Although we have an extended warranty through Mercedes, and although "Crankcase" and "crankcase assembly" are in the warranty, the dealership is saying it's not covered. We are trying to fight this as we know this is a common problem that's covered for Mercedes cars.

Check engine light came on during a summer vacation about 700 miles from home with only 45k miles. Had the code scanned and started researching the forums. Called the local Mercedes dealer and didn't get any help. Forums say that this is a common problem with the M270/274 engine that has been known about for years. Some 'genius' put the PCV valve into an assembly that requires $900 worth of labor to access. PCV valves wear out all the time and they don't think they should make it easily accessible?

I drove the car home since it wasn't yet in limp mode and get a quote for $2,404 from our local dealer. My coworker just replaced his PCV valve on his Honda by himself because it is on top of the engine where it should be. Seriously thinking about moving on from this car after two and a half years. Not sure I can maintain a Mercedes without getting mad at it. I had been considering a C300 for my wife but I think I'll avoid Mercedes in the future.