2012 MERCEDES-BENZ C300 Complaints

While driving recently we noticed that the vehicle pulled to one side while braking, and very hard under quick stop tests. Vehicle handling felt extremely dangerous when performing a hard brake test. An inspection was performed, and the service center found a rotted out rear subframe, and cracking around the suspension mounting brackets. After researching this repair, we found this to be a common problem in this and similar model Mercedes-Benz (MB) vehicles of that vintage. I understand that a recall may have been issued in Canada regarding this issue, but not in the U.S. Mercedes-Benz and their service stations have acknowledged this issue is common but they have not taken action to rectify this serious problem, or to compensate owners for the repair costs, which range from $3500 to $6000 depending on where the vehicle is serviced. We are the first owners of this car. It is barely 10 years old, is regularly maintained, and thoroughly washed during the winter months to remove road salt. A well maintained vehicle should not deteriorate this rapidly from rust, especially a Mercedes-Benz. We feel that it is unacceptable for MB to remain unaccountable for this problem.

Rear subframe failure caused me to loose control of vehicle almost resulting in a serious highway accident. Rear driver side stabilizer subframe mount was completely corroded and broken away from the subframe. There is no other significant corrosion on the subframe. MB claim normal corrosion however the pictures tell a different story.

While performing service inspection, technician found REAR SUB FRAME RUSTED AND READY TO BREAK. Told they needed to show me the problem on the lift, as it was a serious SAFETY ISSUE and should be IMMEDIATELY REPLACED. Dealer and service acknowledged that this is a KNOWN and WIDESPREAD PROBLEM in C Class vehicles. Cost to replace quoted at $4200. No warning - thankfully inspection found before I was in a serious accident! Mercedes should issue recall for failed/corroded frame. Not the "safe" vehicle that Mercedes claims. (Car has been dealer serviced regularly, garaged, and 34,000 miles.) Owners shouldn't have to suddenly come up with $4,200 in order to drive their seemingly normal car. DANGEROUS.

Per the dealership in connection with a regular service, the rear subframe rusted out and became structurally weak and was a safety hazard. The problem was confirmed and repaired by an independent repair shop. From Google searches, this issue does not appear to be an uncommon problem. Car is garaged and receives regular underbody washes for road salt.

While driving, engine stopped, could not steer.. Looks like a defective Electronic Ignition Switch or steering lock! It seems to be a common problem on these cars!!! The car would not start. After 8 attempts, I was able to start car but was afraid to drive it. Could have been a disaster.

This is a followup to a previous report. I now have photos and the actual part that was replaced. While driving on secondary road at 45 mph, braked for stoplight in 2012 Mercedes C300 4matic. Car veered left, rear swung right, and right front dove downward. Luckily regained control and prevented swerving into oncoming traffic. Took car to my regular mechanic and it was determined that the welds on the left rear portion of the rear subframe had rusted out from the inside of the subframe, severing the attachment to the left rear wheel control arms. The car had been inspected 6 months earlier and there was no sign of problem. The failure was catastrophic, not gradual. Upon removal, it was also noted that the right mounting bracket was also in the process of rusting through and failing. When the mechanic called the local Mercedes dealer, the service manager was not surprised and proceeded to outline what parts would be needed to carry out the repair. When I contacted the local Mercedes dealer, myself, they said this wasn’t an uncommon problem, but there was not recall or service bulletin on the problem. Was given a rough quote of $5000 to affect the repair. I also contacted Mercedes Benz USA and was told there were no recalls or service bulletins, but they might be able to provide some “Goodwill Assistance” to offset the expected cost if I had it towed to a MB dealer and got a quote from them. Benzworld.org, an owners forum with over 5 million participants world-wide https://www.benzworld.org/threads/w204-rear-subframes-deterioration.3048088/#post-17965564 has multiple postings about the problem as do other forums including CarProblemZoo.com https://www.carproblemzoo.com/mercedesbenz/c300/suspension-problems.php . This design/manufacturer defect has had recalls in both Europe and Canada. Why this is not being addressed in the US? This sudden failure is potentially life-threatening.

The rear subframe rusted through causing mounting point of the torque link to fail. As a result, the car looses control when braking going sideways. Luckily, I discovered it when testing brakes after pad replacement in a safe setting. To my understanding, there are many other W204/W212 cars affected in the US with that issue. Mercedes so far does not want to take responsibility and recall cars for this issue which is a huge concern.

3 signal Signal light comes one saying abs, another SRS MALFUNCTION, also crushed control inoperable. Car will come one as normal next day car comes on no lights not 1 button work turn signals didn’t work then my car fan came on in the engines the also the when they the electric isn’t working i have to manually shift the gear

The contact's wife owns a 2012 Mercedes-Benz C300. The contact stated that upon taking the vehicle to the dealer to be serviced, he was informed that the subframe was severely corroded and could fracture. The manufacturer was notified of the failure and advised the contact that they could not assist as the vehicle was out of warranty. The vehicle was not repaired. The approximate failure mileage was 43,000.

While driving on secondary road at 45 mph, braked for stoplight in 2012 Mercedes C300 4matic. Car veered left, rear swung right, and right front dove downward. Luckily regained control and prevented swerving into oncoming traffic. Took car to my regular mechanic and it was determined that the welds on the left rear portion of the rear subframe had rusted out from the inside of the subframe, severing the attachment to the left rear wheel control arms. The car had been inspected 6 months earlier and there was no sign of problem. The failure was catastrophic, not gradual. When the mechanic called the local Mercedes dealer, the service manager was not surprised and proceeded to outline what parts would be needed to carry out the repair. When I contacted the local Mercedes dealer, myself, they said this wasn’t an uncommon problem, but there was not recall or service bulletin on the problem. Was given a rough quote of $5000 to affect the repair. I also contacted Mercedes Benz USA and was told there were no recalls or service bulletins, but they might be able to provide some “Goodwill Assistance” to offset the expected cost if I had it towed to a MB dealer and got a quote from them. Benzworld.org, an owners forum with over 5 million participants world-wide https://www.benzworld.org/threads/w204-rear-subframes-deterioration.3048088/#post-17965564 has multiple postings about the problem as do other forums including CarProblemZoo.com https://www.carproblemzoo.com/mercedesbenz/c300/suspension-problems.php . This design/manufacturer defect has had recalls in both Europe and Canada. Why this is not being addressed in the US? This sudden failure is potentially life-threatening.