Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2015 Mercedes-Benz C300 owners, lightly cleaned up (personal details are redacted by NHTSA).
Mercedes Benz via American Service Center in Arlington, VA regarding the service they performed on my 2015 C300 W4 4Door Sedan AWD the following issues have presented: ISSUE: 03MBZZWARN1 ENGINE LIGHT TECH: 901844 PROBLEM: ENGINE HARNESS, ENGINE CONTROL MODULE, CRANKCASE VENT VALVE, AND O2 SENSOR BANK 1 CAUSE: FOUND OIL IN THE ENGINE HARNESS AND ENGINE HARNESS. OIL IS ENTERING THREW [SIC] THE CRANK CASE VENT VALVE. RECOMMEND REPLACING. Approximate miles at the time of this issue: 63,141. Cost of Repair: $8309.58 Yes, the vehicle is available for inspection. Safety concerns: The vehicle is not able to pass an emissions test with the engine light engaged. Per America Service Center in Arlington, VA, which is the only service center that has serviced the vehicle during my ownership, they commented and documented that oil is entering through a vent valve. …
Reported to local dealer and corporate office about the issues with shift module not shifting at random, meaning that the vehicle won't shift from park to drive or reverse, and so forth. The local dealer tried to reprogram the software, but the problem still persists. When plugging in my OBD II & DTC readers, code U0103 appairs which translates to "Lost communication with gear shift control module". My concern with this is that I've had this issue while in traffic, which would make my vehicle a hazard. When it comes to the collision prevention system, the system randomly turns on and off, meaning that when it's needed it might turn on, but when it's not needed it randomly turns on. Once again, addressed this with a local dealer and Mercedes Benz corporate with no avail. …
The contact owns a 2015 Mercedes-Benz C300. The contact stated that while driving at various speeds, the vehicle would intermittently fail to accelerate upon the depression of the accelerator pedal. The contact took the vehicle to an independent mechanic where she was informed that the turbo booster was defective. The contact then took the vehicle to another independent mechanic where the oil circulation and turbo booster were replaced. After the repair, the air bag warning light was illuminated. The vehicle was taken back to the independent mechanic where the vehicle was diagnosed with a defective clockspring. The dealer was notified of the failure and informed her that there were no recalls on the vehicle. The manufacturer was notified of the failure and referred her to the NHTSA. The vehicle had yet to be repaired. The failure mileage was unknown. The VIN was not available.
Rear subframe completely rusted out. While driving on the hwy I heard a loud noise, a couple minutes later I hit the brakes to slow down to get off my exit and after pressing the brakes the car instantly fishtailed sending me sideways across 2 lanes of traffic. Luckily no one was injured or killed. I've seen that the car manufacturer was replacing this issue on models 2008-2015. My vehicle is a 2015 and they are telling me my vehicle is not covered for the issue. The car is not drivable and Mercedes needs to be held accountable. A critical component such as rear subframe completely rusting out in just under 10 years is unheard of and I can't afford to pay 10k to fix it. Please help
My car is the 2015 Mercedes- benz (MB) c 300 4MATIC. The Check engine light is on and off for some months as initially MB dealer said that it's likely due to gas cap defects so we replaced the gas cap. After that, the engine light is still on and off. MB dealer now said $1,760 to replace crankcase vent value and $2870.55 to repair the front differential leaking/reseal. It will cost me a total of $ 4630.55 +tax to repair. The car has only 70,000 miles and kept good maintenance frequently. Right now my car is not safe to drive it so why this car is broke down so quickly. That is not acceptable to us.
Purchased vehicle in march 2024 it went thru emission inspection in 2022 after failing it passed second time . I go for inspection and it fails emission test again just passed two years later. After doing my research Positive Crankcase Ventilation System seems to be a very common problem. It also cost 2000 to fix. Appreciate you time thank you
failed piston wrist pins from early production of mercedes w205 c300. The issue was diagnosed by mercedes of manhattan and could not provide me a fix. Stated that the issue is common with the vehicle and it does not warrant a recall for this issue. i believe its a safety issue and my vehicle only has 60K miles
PVC Pipe to turbo. I am very concerned because this is a reoccurring issue with many owners of C300s. Also, I think it is related to recall number 20V364000 Engine and engine cooling: Engine: Gasoline: Turbo/supercharger. The issue was confirmed by a dealer Check engine light illuminated.
Rear-subframe corrosion at the lower-control-arm mounts has progressed to the point where both arms have play and produce loud metallic bangs while braking or turning at low speed. Two independent shops lifted the car, documented flaking rust around the bushing sleeves, and advised the subframe is structurally compromised and could let a control arm detach under load. The corroded subframe remains installed and can be inspected on request. Safety risk: a detached rear control arm would cause sudden, unpredictable steering and loss of control. The vehicle already pulls right under braking, and feels very unstable in curves Problem has been reproduced and photographed by two independent repair facilities. No manufacturer representative has inspected the vehicle so far. …
On February 9th, during my morning commute on the interstate the car lost power to the drivetrain. Message that displays was "collision assist plus inoperative" along with cruise control inoperative. With an amber ESP light illuminated, there was no engine light on. When this message appeared the car would no longer accelerate (limp mode). In avoidance to being in a rear end collision I quickly pulled over, turned off the car and turned back on. Inoperative message, limp mode and ESP light was cleared. I called dealer to notify. My thought was the battery is a dud (was replaced the day prior), the car needs a software reboot due to the new battery or car was not connected to the "memory saver" correctly. Or the sensors were dirty. So I did the easiest. I washed the car. This problem continued to happen 5-6 times more over the next few days stalling on the freeway at 65-75 MPH. …
Transmission complaints in other C300 years
Frequently asked questions
How common are transmission problems on the 2015 Mercedes-Benz C300?
NHTSA has 20 complaints about the transmission & drivetrain of the 2015 Mercedes-Benz C300, 5% of the model year's 381 complaints.
Is there a recall for 2015 Mercedes-Benz C300 transmission problems?
No. NHTSA lists no transmission & drivetrain recall for the 2015 Mercedes-Benz C300, though it has 11 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 2015 Mercedes-Benz C300 transmission problems start?
Half of the complaints with a recorded mileage happened before about 28,000 miles, and 50% before 25,000 miles.
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.