2015 Mercedes-Benz C300 transmission problems

Filed Oct 30, 2025 · Suspension, Transmission · DE

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

Filed May 29, 2025 · Suspension, Transmission · CT

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. Additional component failures possibly linked to the same progressive chassis stress: premature wear of both front CV axles; timing-chain stretch with worn guides; slack oil-pump chain; upper & lower oil-pan gasket leaks; water-pump seepage; right engine-mount collapse; persistent misfire traced to a loose intake-hose clamp; transmission-cooler hose clip released under pressure, dumping all ATF and destroying the automatic transmission; excessive play in all four lower control-arm bushings. The transmission and the other components were replaced 1-2 months before the subframe bro History: A faint clank from the rear suspension first appeared roughly three years into ownership. Dealer service dismissed it as “normal noise,” and warranty would not cover “loud clanks,” so the issue went unaddressed. The noise has grown steadily into the current condition, suggesting long-term subframe corrosion that was never inspected or remediated. No collision, flood, or off-road use; the car has typical Northeast winter-salt exposure. The failure pattern matches subframe-corrosion cases already acknowledged by the manufacturer on this model, although this serial number is not yet included in the official campaign.

Filed Jan 30, 2025 · Engine, Transmission · NY

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

Filed Sep 24, 2024 · Transmission · OR

Known/ common issue with the positive crankcase ventilation regularly valve on my 2015 c300.

Filed Aug 8, 2024 · Engine, Fuel system · MD

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

Filed Jul 10, 2023 · Transmission · CT

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.

Filed May 26, 2023 · Engine, Fuel system · MD

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. My additional concerns are: If an odorless fume is passing into the passenger cabin and the vehicle can not pass state emissions these are immediate concerns. The service center advices that I may continue to drive the vehicle. However, I am concerned should the oil fully empty without warning the vehicle may fail while in use on a dangerous roadway due to cause and effect of additional unknown maintenance related operational co-dependent mechanical components.

Filed Mar 27, 2023 · Transmission · ID

PVC valve shouldn’t fail and each time it does it is around 2k dollars.

Filed Nov 17, 2022 · Engine, Transmission · CT

This occurred after an oil change. it is the P052E code crankcase ventilation code.

Filed Jul 29, 2022 · Driver assistance, Transmission · KS

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. My concerns here is that the vehicle could prematurely brake causing an accident or not brake at all causing an accident.