2019 Mercedes-Benz C-Class Powertrain & Transmission Problems

Shifting gears when stopped and the car lunged forward while I was stopped at a red light. I almost hit the car in front of me at the red light. Very rough gear changes and changing out of the correct gear to the wrong one and then back into another one. Severe speed changes - jerking the car back or it lunges forward, while driving results in loss of reasonable control of the vehicle and inability to to shift correctly out of traffic. Mercedes benz has a technical service bulletin on this problem and is aware that the 9G-Tronic - internally designated as the 725 transmission (fault code P07B700) is defective and known to experience sudden pressure sensor failures or valve body faults within the transmission control unit which prevents the car from shifting gears corrected or forces limp mode. The repair is a minimum of $5,200. MBZ has known this is a defect and wide spread issue but unwilling to contribute to the repair or recall or respond to my letters and the inquiries of other vehicle owners I have spoken to that have the same issues. It is a catastrophic mechanical failure from a sensor they know is bad and is occurring shortly after warranties are expiring. It is putting all of our lives and the lives of others at risk of an accident due to the failure of their part. Thank you for your consideration.

This vehicle was brought to an authorized Mercedes-Benz dealership for regularly scheduled maintenance. Shortly after this service, the vehicle began experiencing significant issues including difficulty accelerating, engine hesitation while driving, and noticeable shaking at idle. This car has never overheated. The vehicle was returned to the dealership for inspection. The dealership diagnosed a cracked cylinder head and advised that the repair requires replacement of the cylinder head at an estimated cost of approximately $11,000. The failed component is available for inspection and the vehicle is currently at the dealership. The vehicle has approximately 46,000 miles, has been regularly maintained, garaged, and driven under normal conditions. These symptoms created engine performance issues that could result in loss of power or inability to accelerate while driving, creating a potential safety risk, especially in traffic or at highway speeds. I regularly transport my young grandchild in this vehicle. The possibility of sudden engine failure, loss of power, or breakdown while driving raises significant safety concerns for myself and any passengers, particularly a young child. The failure has been confirmed by an authorized Mercedes-Benz service center. During my own research, I discovered there have been recalls involving similar engines for the same model year, as well as multiple owner complaints reporting similar engine or cylinder head failures on this vehicle. I contacted Mercedes-Benz customer care on December 17, 2025, after receiving the dealership diagnosis, and was advised that I would receive a response within 72 hours. As of today, I have not received any response. I attempted to call customer care again, but the phone system would not accept a voicemail and no representative answered. My case number with Mercedes-Benz is 19653254. No prior abuse, misuse, or abnormal driving conditions occurred. The vehicle was properly maintained.

Engine stuttered violently while driving 40mph. Check engine light was coming on and off. I immediately pulled to the roadside for my safety. I put the vehicle in park and cycled the ignition and the problem disappeared. the vehicle stuttered twice a few miles as I was taking the vehicle to the garage. I haven't had it serviced yet. The vehicle was serviced in the past for a Recall that had similar issues.

The contact owns a 2019 Mercedes-Benz C 300. The contact stated that while driving 65 MPH, the vehicle inadvertently lost motive power, and was unable to accelerate above 25 MPH. The check engine warning light was illuminated. The vehicle was taken to the dealer, who determined that the PCM required a software update. The vehicle was repaired. The manufacturer was notified of the failure, a case was opened, and the contact was referred to the NHTSA Hotline for assistance. The failure mileage was 36,000.

WAS STOPPED AT RED LIGHT. WHEN IT TURNED GREEN, PULLED UP WAITING FOR TRAFFIC TO CLEAR FOR A LEFT TURN; ONCE TRAFFIC CLEARED, ATTEMPTED TO ACCELERATE THROUGH TURN BUT VEHICLE WOULD NOT MOVE. MOVED FOOT BACK TO BRAKE THEN TO GAS, STILL NO MOVED. TRIED TO CONFIRM VEHICLE WAS IN DRIVE, NOTICED MESSAGE ON INSTRUMENT PANEL "TRANSMISSION FAILURE". VEHICLE WOULD NOT SHIFT INTO OR OUT OF ANY GEAR, AND WOULD NOT MOVE. SHUT OFF VEHICLE AND RESTARTED, VEHICLE THEN SHIFTED AND MOVED NORMALLY. WAS ABLE TO CLEAR INTERSECTION.