Which parts fail
Components named in complaints (engine, cooling system, oil leaks, timing chain, exhaust).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2017 Mercedes-Benz C300 owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2017 Mercedes-Benz C300. While driving at approximately 15 mph, the contact observed smoke emanating from under the hood. The vehicle was driven to her work location and parked. Upon exiting the vehicle and opening the hood, she observed orange flames coming from the engine compartment. A parking attendant extinguished the fire, and a police and/or fire report was filed. The vehicle was towed to a dealer and diagnosed with a fuel line leak that caused the engine harness to come apart. The leaking fuel hose from the high-pressure fuel pump caused damage to the high-pressure pump, engine harness, vacuum transducer, and coolant feed line from the thermostat to the firewall. The following components needed replacement: high-pressure fuel pump, rubber fuel hose, engine harness, pressure transducer, and intake manifold. The vehicle was repaired. …
The contact owns a 2017 Mercedes-Benz C300. The contact stated while driving 45-50 MPH, the vehicle stalled inadvertently and would not exceed 3 MPH. There was no warning light illuminated. The contact was unable to veer to the side of the roadway. The contact turned on the hazard lights. The contact turned off and restarted the vehicle however, the vehicle would not exceed 5 MPH and was making abnormal sounds. The contact veered to the side of the road for approximately 4 hours until there was no longer traffic on the roadway. The contact proceeded to drive at 5 MPH to her residence less than two miles away. The manufacturer was notified of the failure and assisted with towing the vehicle to the dealer to be diagnosed. The contact was informed that the piston rings had blown out and the engine needed to be replaced. …
The contact owns a 2017 Mercedes-Benz C300. The contact stated that while at a stop light the vehicle stalled. There were no warning lights illuminated. The vehicle was taken to the local dealer where it was diagnosed and determined that the battery cable needed to be replaced. The vehicle was repaired but the failure recurred. The vehicle was taken back to the local dealer where it was diagnosed that an update to the powertrain software was needed, and the transmission pump needed to be replaced. The vehicle was repaired but the failure persisted. The contact called the local dealer, and it was recommended that the transmission be replaced. The vehicle was not repaired. The manufacturer was contacted. The failure mileage was approximately 80,000.
The contact owns a 2017Mercedes-Benz C300. The contact stated that upon having the vehicle inspected, the check engine warning light illuminated. The vehicle was diagnosed and produced code: P052E. The vehicle was then taken to an independent mechanic where it was diagnosed that the Positive Crankcase Ventilation (PCV) failed and needed to be replaced. The vehicle was repaired. The dealer and manufacturer were notified of the failure and confirmed that the VIN was not included in a recall. The failure mileage was approximately 53,000.
The contact owns a 2017 Mercedes-Benz C300. The contact had received notification of NHTSA Campaign Number: 21V032000 (Seat Belts). The vehicle was taken to a local dealer and the recall repair was performed; however, upon retrieving the vehicle, the check engine warning light illuminated upon starting the vehicle. The vehicle was taken back to the dealer and remained in the dealer possession. The manufacturer was not notified of the failure. The vehicle was not repaired. The failure mileage was approximately 34,000.
I am reporting a serious vehicle safety hazard caused by improper and unsafe repair work performed by USA Platinum Motor, located at 1221 California Lane #126B, Arlington, TX. I brought my 2017 Mercedes-Benz C300 in for a cold start rattle with no warning lights or prior issues. The shop diagnosed a loose timing chain and I authorized the repair. After the repairs, the vehicle was returned with critical safety defects, including a loose fuel pump, unsecured fuel line, missing bolts, and improperly reassembled engine components. Shortly after pickup, the car experienced loss of acceleration on the interstate, a strong odor of fuel, and a sudden loss of power, creating a dangerous and life-threatening situation. The vehicle had to be towed back to the shop. The manager, who is not a certified mechanic, admitted he personally "fixed" the issue by tightening the fuel pump himself. …
my 2017 Mercedes C300 experienced what appears to be a very common engine fault with the W205 engine. It involves the "PCV" valve and the engine code fault is P052E. When this fault occurs the engine will stall and sputter. My wife and daughter were in my car last week and it stalled at an intersection which could have resulted in an accident, but luckily the school crossing guards were there to stop traffic and allow her to restart the car and get to the side of the road. The check engine light had previously been on and off for sometime so I had my local Mavis check what the light was on for and they gave me the fault code. I did not think it was anything that serious because the car ran fine. The car was towed today to Mercedes to officially diagnosis the problem
Diagnosis code P052E PCV regulator valve replacement/crankcase replacement. Dealership does not want to acknowledge code while car was under warranty despite proof that it existed when check engine was diagnosed. Now code keeps coming back with check engine light on dashboard. To replace part, the engine has to be taken down since the crankcase is inside the engine. This is a malfunction during assembly/manufacturing, it is impossible to damage part while under usage. Mercedes Benz should be held responsible for part replacement and labor. I urge you to investigate this matter with other clients and ask the manufacturer to replace part and pay for labor.
My car suddenly turned off at a stop sign. After I restarted it, it turned back on and my engine light turned on. I called the dealership and after inspection I was told that the valve for my crankcase was malfunctioning. The total cost, including both parts and labor are $1775. I have seen many complaints regarding this issue with the same vehicle. It is apparent that a recall should've been issued for this months ago. It is truly a safety issue when the car turns off at a stop sign or a ramp. I could've been hit while my car was stalling on a ramp exiting major highway. I implore you to rectify this issue immediately before someone gets hurt.
At approximately 26,500 miles of use, the check engine light came on in my Mercedes Benz C300. I brought the vehicle to the dealership and they informed me that the diagnosis was a crankcase vent valve malfunction. The MB fault code is P52E71. After paying Mercedes to fix the issue, I found forums on the internet where many other MB owners reported the same issue at around the same mileage. Being that this seems to be a common malfunction with the C300, I believe that it should be considered as a recall issue. I don't know what could have happened if I didn't service the vehicle, but any engine issue is dangerous while a vehicle is in motion.
Engine complaints in other C300 years
Frequently asked questions
How common are engine problems on the 2017 Mercedes-Benz C300?
NHTSA has 79 complaints about the engine & cooling of the 2017 Mercedes-Benz C300, 37% of the model year's 216 complaints. The component named most often is exhaust system › emission control › crankcase (pcv) (1 mentions).
Is there a recall for 2017 Mercedes-Benz C300 engine problems?
No. NHTSA lists no engine & cooling recall for the 2017 Mercedes-Benz C300, though it has 15 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2017 Mercedes-Benz C300 engine problems start?
Half of the complaints with a recorded mileage happened before about 48,000 miles, and 10% before 25,000 miles.
Is it dangerous?
Owners linked 0 crashes, 1 fire and 0 injuries to engine & cooling problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.