CEL on 2013 C250
Took it to the dealer, they did a compression check on all 4 cylinders, checked #1 coil and #1 plug, all normal (not replaced).
Dealer then upgraded old M. E. software(???) which they said was not up to date. We will see if this fixes problem.
I read your posts and the others, as too have a similar misfire issue on a C203 C180 Kompressor (four cyl). Random and know is does have an O2 issue fault. I done all the basics, new plugs, coils, cleaned connectors, air filter checked, air box etc. Mine runs for 10/15 kms before it looses one cylinder and then when cooled or the next day, runs fine again.
I had radon issues when I purchased this car with the rear lights, which I traced to the rear SAM unit being faulty. This was replaced and all lights worked again, however I lost the lower fog lights two days later. These are fed from the front SAM, so was heading towards a front SAM issue too, for my misfire ! The car is new to me and had some block screen channel drains, which I suspected could have resulted in water ingress to the front SAM. Your post has sent me in the O2 direction, being the cheaper and simpler option first, so greatly appreciate you posting the fix for your car.
many thanks
joe


