Failed positive crankcase ventilator after 40,000 miles common problem regulating oil consumption to the engine. Causing oil burn, oil leak, inconsistent oil ventilation. Dealer is aware of the problem. Engine light is on with code P052E. Commonly reported problem for this model on the internet.

- Smithtown, NY, USA

at 67000 miles the check engine light came on and is was engine code p052e crankcase ventilation regulator valve failure. This failure will cause the ending to exhaust increased contaniments in to the air. This is a know problem by MBUSA and they have changed the part design on new vehicles, this problems comes up right after the cars warranty and they cost to repair is in excess of $2500. For this to be an emission know problem by MBUSA a recall should be issued and this problem corrected under the recall process of the NHTSA ASAP. This has been reported to MBUSA and they have been zero help in this matter. The NHTSA is here to protect our citizens and environment and hopefully you will continue to do so.

- Andover, KS, USA

CYLINDER 1 SPARK PLUGS IS DAMAGED DUE TO PISTON DAMAGE, HOLE IN PISTON. IF EXTRA DAMAGE IS FOUND ON TEAR DOWN, COMPLETE ENGINE REPLACEMENT. This is direct from the repair facilities reports. While driving my 2018 C-300 there was smoking out of tail pipe, a rough vibration, hard to control the vehicle and it was starting to lose power. Not a good situation, had to pull over and have vehicle towed to the dealership. Worst part is this is a vehicle used to transport my 5 children to and from school and activities. My 16 year old also drives this vehicle, had he been driving this with this happening to him, the outcome could have been catastrophic. Vehicle has been inspected by 2 facilities; first was a certified Mercedes Benz repair facility and the second was the service dept. of the Mercedes Benz dealership I have serviced at for over 10 years. Mercedes refuses to cover repair costs or even acknowledge the major vehicle malfunction and safety issue this presents., which is in my view ridiculous as cracked piston is not something that normally happens as the result of normal wear and tear, especially in a 3 year old luxury car. I have read several blogs on this same issue, Mercedesworld.org with over 400K members, reddit.com, benzworld.org, metrisforum.org, and numerous others. Please review these there are numerous people dealing with this and Mercedes is refusing to acknowledge. In addition, our Mercedes Benz service rep said these pistons were changed out in the 2019 model and newer due to these issues, he said he continues to see this issue with these models and advised Mercedes is well aware.

- Scottsdale, AZ, USA