Home · 2018 Mercedes-benz C-class Phev · Complaints

What 125 owners told NHTSA about the 2018 Mercedes-benz C-class Phev

These are the actual owner complaints behind this car’s reliability verdict, filed with the federal government, unedited. They’re unverified reports, not confirmed defects: read them as leads for your pre-purchase inspection, not a diagnosis.

All (125)Crash / fire / injury (5)Engine (39)Body & structure (15)Steering (13)Electrical system (12)Fuel system (10)Transmission & drivetrain (6)Airbags (5)Communication (5)Tires (5)Wheels (5)

39 of 125 complaints match · Engine · clear filters · page 2 of 2

Feb 21, 2023EngineFuel system

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.

NHTSA ODI 11508445

Feb 21, 2023EngineFuel system

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.

NHTSA ODI 11508446

Feb 17, 2023Engine

Code P052E just like all 2.0 turbo Mercedes Benz engines will get. This is a engineering defect and the cars with these engines should be recalled. I have researched and read that even after repaired this expensive engine defect will re-occur about every 35000 miles.

NHTSA ODI 11507887

Jan 24, 2023Engine

2018 Mercedes C300. P052E check engine code. Positive Crankcase Ventilation failed with less than 28K miles. Common reported problem but not covered after warranty period, even with extended warranty addition. It's a major part of the engine function and 6 hours of labor to replace. Mercedes Benz should cover this type of fault on the design.

NHTSA ODI 11503416

Dec 23, 2022Engine

initial observation started happening intermittently a week before the car become inoperable. When the vehicle came to a stop like at a light the engine would sound like it was going to almost turn off like a rattle noise and a popping sound or like I hit a plastic bag sound on acceleration. Then the day it broke down I was merging onto interstate 15 I heard the same popping sound, the engine light came on and my car broke down. My car was towed to Mercedes Benz of Ontario and inspected by technicians there and by the claims inspector for safe guard international (service protection plan i purchased with the vehicle)I was told it needed an entire new engine due to cracks in two pistons, etc. This was confirmed by the claims inspector with safe guard. This car was well maintained and only had 69,000 miles on it. I don’t think I need to explain the how my safety or the safety of others was at risk when my car breaks down in the middle lane on interstate 15 in California and I have to get over to the shoulder. This vehicle is available for inspection if needed.

NHTSA ODI 11498619

Aug 16, 2022Engine

Engine light appears due to P052e code “positive crankcase ventilation regulatory valve”. Part failed prematurely and appears to be a common problem in make/model. May cause engine damage due to inability to clear combustion gases in the crankcase.

NHTSA ODI 11479681

Aug 9, 2022Engine

CRACKED PISTON AT 68K MILES The vehicle is very well maintained, only 68k miles, has had every oil change, only takes premium gas. I was driving it when the check engine light went on and the vehicle began shaking violently. After towing the vehicle to the Mercedes Benz dealership, they informed me that the piston cracked and they could not articulate a reason why this would happen.

NHTSA ODI 11478301

Jul 30, 2022Transmission & drivetrainEngine

Engine light ON with DTC code P052E

NHTSA ODI 11476706

Jul 9, 2022Engine

My car engine shutoff at stop lights. it happened 3 times, the other 2 incidents happened at parking lots.

NHTSA ODI 11473032

Feb 25, 2022Engine

My Mercedes C300 2018 only have 33k miles on it, but I was leaking oil and gas from the positive crankcase ventilation valve which is not environment friendly. As I know many other who own Mercedes also have the same problem.

NHTSA ODI 11454009

Jan 4, 2022Transmission & drivetrainEngineFuel system

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.

NHTSA ODI 11446178

Dec 7, 2019Engine

WHEN AT A STOP THE ENGINE WILL NOT RESTART SOMETIMES. I HAVE TO START THE ENGINE MANUALLY. THIS HAS HAPPENED TO ME FOUR TIMES IN 5 MONTHS .

NHTSA ODI 11287701

Sep 23, 2019Electrical systemEngine

TL* THE CONTACT OWNS A 2018 MERCEDES-BENZ C300. WHILE OPERATING THE VEHICLE, THE CONTACT NOTICED A BURNT CRAYON ODOR INSIDE THE VEHICLE. THE ODOR MADE IT DIFFICULT TO BREATHE INSIDE THE VEHICLE. THE VEHICLE WAS TAKEN TO MERCEDES-BENZ OF GOLDENS BRIDGE (321 NY-22, GOLDENS BRIDGE, NY 10526), BUT THE CAUSE OF THE FAILURE WAS NOT DETERMINED. THE MANUFACTURER WAS NOTIFIED OF THE FAILURE. THE FAILURE MILEAGE WAS 14,000.

NHTSA ODI 11257284

Apr 15, 2019Transmission & drivetrainWheelsEngine

PURCHASED CAR JULY 2018. A/C LEAK IN AUG 2018 AND MARCH 2019; DEALER LOCATE LEAK. FRONT TIRE BLOWOUT WITHIN 6 MONTHS OF PURCHASE (DEC 2018) TRAVELING ON FREEWAY EVENING TIME APPROX 65 MPH; UNKNOWN REASON . SAME SIDE FRONT TIRE BLOW OUT 4 MONTHS LATER (MARCH 2019) DRIVING LATE EVENING ON A MAIN BOULEVARD TRAVELING 25 MPH AND RIGHT FRONT TIRE SHREDDED; HIT MINOR POTHOLE BOTH FRONT TIRES HAD TO BE REPLACED AND THE CAR ALIGNMENT CORRECTED. 1 MONTH LATER (APRIL 2019) RIGHT REAR TIRE LOOSING PSI EVERY 45 MILES; DEALER COULD NOT DETECT LEAK, POSSIBLE VALVE STEM. SAME VISIT DEALER REPLACED TWO REAR LEAKING SHOCK ABSORBERS AND NOTED RIGHT REAR TIRE HAD UNEVEN WEAR /RECOMMEND REPLACEMENT; TIRES HAVE 21,000 MILES. I WILL HAVE TO RETURN THE CAR TO THE DEALER FOR REPAIR. THE TRANSMISSION HAS A VERY HARD SHIFT WHEN I ACCELERATE MORE THAN MODERATE; THE HARD SHIFT CAUSES THE VEHICLE TO PAUSE AND JAR /JERK ABRUPTLY THAT ALMOST SEEMS LIKE YOU HIT SOMETHING. I HAD REPORTED THE ISSUE WITHIN 7 DAYS OF PURCHASE AND I WAS TOLD AMGS HAVE HARD SHIFTS. WHEN I INSISTED THERE WAS AN ISSUE A SECOND TIME IN MARCH 2019; THE ISSUE WAS ADDRESSED AND I WAS TOLD IT WAS THE COMPUTER SOFTWARE THAT REQUIRED AN UPDATE; THE UPDATE TEMPORARILY CORRECTED THE PROBLEM FOR APPROX 1 MONTH. THE VEHICLE HAS BEEN OUT OF SERVICE FOR APPROXIMATELY 13 DAYS SINCE PURCHASED 9 MONTHS AGO IN JULY 2018.

NHTSA ODI 11196192

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Working with the data? Download all 125 complaints as CSV · fetched from NHTSA July 21, 2026

How to use these: a complaint is one owner’s report, filed voluntarily and published unverified. Patterns matter more than any single story. If several owners describe the same failure at similar mileage, put that system at the top of your pre-purchase inspection list. Back to the full 2018 Mercedes-benz C-class Phev verdict →