Mercedes-Benz C300 sudden acceleration problems

Filed Aug 16, 2026 · Transmission · CA

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.

Filed Jul 30, 2025 · Brakes, Driver assistance · NY · crash

The vehicle appears to have experienced a braking system malfunction, possibly involving the brake-by-wire system, electronic stability control (ESC), or unintended acceleration event. When the brake pedal was fully depressed, the car suddenly and uncontrollably accelerated forward into a cinder block wall. After the incident, it was observed that only the left-side tires left skid marks, indicating an apparent brake imbalance or failure on the right side. The vehicle is available for inspection upon request. My safety and the safety of others were severely compromised. My daughter and I were in the car during this and are extremely traumatized. Despite pressing the brake pedal, the vehicle accelerated forward and crashed into a cinder block wall, which could have resulted in serious injury or death had a person, pedestrian, or oncoming vehicle been in front. This type of malfunction poses a critical risk of high-speed unintended collisions in public or residential areas. As of now, the problem has not yet been reproduced or confirmed by a dealer or service center, but further inspection is pending. I am requesting a full diagnostic evaluation, including electronic and mechanical systems related to throttle and braking. The vehicle has not yet been inspected by Mercedes-Benz, police, or insurance representatives, but the car is in the possession of a Mercedes’ collision center. NO, there were no warning lamps, messages, or unusual symptoms on the dashboard prior to the event. The vehicle gave no indication of mechanical or electronic failure before the sudden acceleration occurred.

Filed Jul 22, 2022 · Electrical, Fuel system · MD · crash

I was moving my car from one parking space to another space in front of my house. As I was pulling into the new space, I stopped to check the position of my car. As I lifted my foot off the brake, the car unexpectedly started to lurch forward. When I released the brake pedal, the car suddenly accelerated and proceeded to jump the curb and run into the front of my house. Luckily, no one was injured. There was some damage to the exterior of my house. I have reported this issue to the car manufacturer, Mercedes Benz. In response, they have opened a case to research it further.

Filed Oct 2, 2020 · Acceleration · FL · crash

2011 mercedes benz c300. Consumer writes in regards to unintended acceleration. *ld the consumer stated the vehicle acclerated over a cement parking barrier and into a tree. The dealer was notified.

Filed Dec 2, 2019 · Acceleration, Body · 8,000 miles · PA · crash

Sudden acceleration after pulling very slowly into parking space. Almost stopped. Car suddenly accelerated, jumped a curb from, went up an embankment and hit a tree. Was able to reverse and back down. It will take a month for body work. Notified mercedes dealer. They will run diagnostics on jan. 7.

Filed Mar 2, 2017 · Transmission · 3,592 miles · FL

When at a red light and the car is idling, all of a sudden the car jerks forward. If the brake is not engaged hard, I have experienced the car feeling like it will lunge forward. This occurs each and every time I am idling at a red light.

Filed Sep 17, 2016 · Acceleration, Body · 8,999 miles · VA · crash

After stopping and waiting at a traffic light for 15-30 seconds, I had my feet on the brakes and left turn indicator on. The "hold" option to lock my brakes was not engaged. The car was stationary. Without warning, the car shifted into drive and jolted forward into the vehicle ahead of me at the light. (I was the second car in line, and I stopped about a half car length behind the other driver.) the acceleration was not a typical, gradual movement associated with what happens when I release my foot from the brake to drive. It was a sudden and jarring jump regardless of the fact that my foot never left the brake. I tried to press the brakes multiple times to stop the forward movement, but my car hit the vehicle in front of me twice. The steel bumper of the other vehicle was not damaged. The front area of my hood (emblem and grill) were crushed. I reported earlier electronic issues to my local dealership as notable oddities, but none made me this concerned about safety of others, my passengers, and myself. As recently as a week earlier, my rear-view camera froze and locked as I was reversing into my garage, so had I trusted the screen in my car, I would have reversed another 5-10 feet into my garage. I could not unfreeze it without putting the car back into drive and restarting my car. Months earlier, the sensor on my side mirrors started to go off without any other source of danger or collision on vacant streets. The air pressure alert warned that my tires were becoming dangerously flat; however, en route to the gas station, the pressure monitor noted that all tires were now returning to normal pressure levels and no inflation was needed. There have been many peculiar events with this new c300 in recent months, but my primary concern as a caregiver is the sudden acceleration from a stopped position--or from any position--without my direction or intent.

Filed Mar 15, 2016 · Acceleration, Brakes · 22,000 miles · GA · crash · 1 injury

While making a right turn into a parking lot at low speed accelerator pedal not depressed the vehicle suddenly accelerated. When brakes were depressed they failed and did not stop nor slow the vehicle. Car crashed into the building. Air bags additionally did not deploy as car hit building in corner at center of front. Minor injury to driver from seat belt restraint.

Filed Apr 28, 2015 · Acceleration · 11,000 miles · PA · crash · 1 injury

Tl* the contact owns a 2014 mercedes benz c300. When the ignition was turned to the on position and the vehicle was shifted into drive with the brake pedal depressed, the vehicle accelerated without warning. The vehicle crashed into a traffic light pole. The contact suffered lacerations to the head, muscle damage to the legs, and a fracture on the eye socket. The contact received medical attention. A police report was filed. The vehicle was towed to the contact's insurance company. The manufacturer was made aware of the failure. The approximate failure mileage was 11,000.

Filed Aug 28, 2014 · Acceleration, Airbags · 24,000 miles · NY · crash · 1 injury

Tl* the contact owns a 2013 mercedes benz c300. While exiting the garage, the vehicle over accelerated on its own when the contact depressed the accelerator pedal. The contact crashed the vehicle into a concrete building and the air bags failed to deploy. The contact sustained a concussion and bruising to the stomach, which required medical attention. A police report was not filed. The vehicle was towed to an independent mechanic. The vehicle had not been repaired and the contact was waiting for the manufacturer to conduct an investigation. The approximate failure mileage was 24,000.