Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2009 Mercedes-Benz C300 owners, lightly cleaned up (personal details are redacted by NHTSA).
I took my vehicle to the Mercedes dealer for inspection on 7/13/22. It passed inspection, but I was told that the brake lines were very corroded and they recommended replacement before driving. Their cost to repair was $2825. I only have 54,000 miles on the vehicle. I checked on the internet to see if there were any other reported brake line issues with a 2009 Mercedes C300 and was shocked to see how many people had the same issue, some reporting that they lost brake power and had a very terrifying experience. Of course I am now afraid to drive the vehicle and not sure what my course of action will be. With the number of reported incidents, I feel that Mercedes used inferior materials that corrode readily and should have some accountability in remedying the situation. I am including some photos of the corrosion that were provided to me by the dealer.
The contact owns a 2009 Mercedes-Benz C300. The contact stated while driving and activating the turn signals, the taillights were inoperable. Additionally, the contact stated while driving and depressing the brake pedal to come to a stop, the brake lights were significantly dimmed except for the third brake light. The vehicle was taken to the dealer, where it was diagnosed with electrical failure. The vehicle was not repaired. The contact related the failure to NHTSA Campaign Number: 14V177000 (Exterior Lighting); however, the VIN was not included. The manufacturer was notified of the failure and informed the contact that they could not assist because the VIN was not included in the recall. The manufacturer referred the contact to the NHTSA Hotline for assistance. The failure mileage was unknown.
Went to the Mercedes dealership service department to replace the rear subframe that suddenly broke while I was driving due to extreme rust/corrosion. The dealership stated that it was being covered under the extended warranty due to the recall related to the rust/corrosion issue with the subframe. I was advised by the mechanic that the brake lines will need to be replaced due to extreme rust/corrosion in the rear at the same exact location of the rear subframe, making the vehicle very dangerous to drive because the brake lines could break at any moment and cause sudden brake failure. I was quoted a very significant amount to replace the rusted brake lines and per the dealership, it will not be covered under any extended warranty and/or recall.
Suspension Cross-Member - Mercedes-Benz (204-350-01-41) Driving regularly suddenly fill like the rear passenger side tire moved unevenly, then went to the tire shop, and when they take out the tire see how the rear frame was rusted and broken in a straight line exactly in the middle of the tire hole area. Then start to check used cars to donate that part and All of them have the same trouble in that piece, so I decided to review the frame and discover that the rust begins to damage the opposite side too, so I'm pretty sure is a component failure in metal and materials more than simple rust.
The brake lines and subframe were completely rusted and the vehicle was unsafe to drive. Dealer confirmed at regular service appointment. I have documentation and competed all regular maintenance. Dealer would not cover costs for what appears to be a major defect. I had another shop replace the brake lines and subframe.
Tl* the contact owns a 2009 Mercedes-Benz C300. While stopped at a red light, the engine revved and the vehicle accelerated. The brake pedal was depressed, but failed and the contact crashed into the rear of another vehicle. The air bags failed to deploy. A police report was filed and there were no injuries the vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The approximate failure mileage was 54,000. Updated 02/21/17 updated 9/5/18
I was driving on the parkway at ~40 MPH and attempted to slow down by stepping on the brake. The car did not slow down but accelerated. And struck the car in front of me. Every time I pressed on the brake, the car accelerated so that the car struck the car in front twice. I tried to turn off the ignition and was unable to. Finally, I pushed hard on the brake enough to slow it down and I was ten able to put the car in neutral. The engine raced but I was then able to turn it off. Despite damage to the front of the vehicle, the airbags did not deploy.
Tl* the contact owns a 2009 Mercedes Benz C300. While attempting to start the engine, the vehicle failed to turn on and the steering lock engaged. The vehicle was towed to the dealer who replaced the steering lock and the control unit. There was no further information available. After retrieving the vehicle and driving, the brake ebr, ABS, ESP and power steering failure messages appeared. The cause of the failure was not diagnosed. The manufacturer was notified. The failure mileage was 63,033.
This vehicle had a failure upon start that eliminated a number of safety features. When I started the car, I received three errors that the following were disabled: electrical brake (ABS, emergency brake, traction control), cruise control, and power steering. Loss of these made the car unsafe to drive.
At 5:00 pm, I was driving the Mercedes Benz C300, year 2009, 9010 miles in the parking lot of ymca in la Canada, ca at 3 miles/hr. I prepared to stop the car and stepped on the brake, suddenly, the engine rev up and accelerated. The car jumped over the stop bumper but I pressed very hard on the brake and finally the car stopped and the engine was off. The front of the car was about 2 feet from the wall at the parking lot. I was so scared because it was the first time I experienced the unintended acceleration. I went to the gym and at 6:30 pm I drove the car back home, it is about 6 miles from my house. I really feel unsafe with my almost brand new mb. I'll take off for work next Monday and will take the car to the dealer for checking. I was lucky this time with no damage or injury because I was driving very slowly in the parking lot and ready to stop. …
Brake complaints in other C300 years
Frequently asked questions
How common are brake problems on the 2009 Mercedes-Benz C300?
NHTSA has 21 complaints about the brakes of the 2009 Mercedes-Benz C300, 4% of the model year's 576 complaints.
Is there a recall for 2009 Mercedes-Benz C300 brake problems?
No. NHTSA lists no brakes recall for the 2009 Mercedes-Benz C300, though it has 8 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 2009 Mercedes-Benz C300 brake problems start?
Half of the complaints with a recorded mileage happened before about 53,000 miles, and 15% before 25,000 miles.
Is it dangerous?
Owners linked 2 crashes, 0 fires and 1 injury to brakes 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.