Mercedes-Benz C300 grinding brakes problems

Filed Jan 20, 2026 · Visibility · CA

I am reporting a safety defect involving the panoramic sunroof on my 2021Mercedes-Benz Coop vehicle. The panoramic sunroof has malfunctioned due to an apparent design or manufacturing defect. The sunroof fails to open / close and makes grinding or popping noises which malfunctioned unexpectedly. This issue occurred without misuse and during normal operation of the vehicle. The defect creates a safety concern because it can distract the driver, allow water intrusion that may affect electrical components, and/or cause sudden glass or mechanical failure while driving. The vehicle has been taken to a Mercedes-Benz dealership for diagnosis and the issue was not resolved due to denied coverage. I was informed that the repair would be costly despite the issue appearing to be a known defect in Mercedes-Benz panoramic sunroof systems. I believe this defect may affect other Mercedes-Benz vehicles with panoramic sunroofs and should be investigated for a potential safety defect or recall.

Filed Jan 19, 2026 · Brakes, Wheels · OH

Rear brakes backing plates rotted prematurely despite garage kept and well maintained status. While driving, noticed loud scraping and grinding noises from the rear left wheel. Took to mechanic and he found severe rust, with deep corrosion and flaking "rotted". He said I was lucky because this was very close to causing the entire brake assembly to fail, which would lead to serious braking problems or "locked out wheel" and loss of control on a highway which would have put me and others at risk. Had similar rust issues with this car that were fixed in the recent past including rusted brake lines and rusted rear subframe. There is definitely something wrong with the manufacturing as the rear subframe had been recalled and got it fixed that way less than a year ago.

Filed Jun 16, 2025 · Steering · NJ

Over the past month, my 2020 Mercedes-Benz C300 has been experiencing unexpected and increasingly concerning issues with the steering. These problems began suddenly and without any prior warning signs. Initially, the steering has been making grinding sounds more usual, particularly at lower speeds and when making tight turns. Over the following weeks, the issue became more pronounced, with occasional instances of the steering wheel resisting movement or feeling delayed in its response. At times, it feels as if the power steering system is intermittently failing or underperforming. There have been no warning lights on the dashboard, and I have not been involved in any recent accidents or incidents that could have caused physical damage to the steering system. I have maintained the vehicle in accordance with the manufacturer's guidelines, including regular servicing. but there the person before me had been in a accident and it may have been the dealership i bought it off of failed to fix it

Filed May 17, 2024 · NC

While driving on the highway, I tried to open my panoramic sunroof, it made a grinding sound and was stuck in the open position with one corner for the sunroof slanted higher than the other. I was afraid that the sunroof would shatter or that the wind would blow off components. Afterward, the sunroof would not close even after I took it to the dealership. They informed me that they could not close the sunroof and my only option was to repair it for $4,000 or buy another car. After looking at the costs of replacement cars, I decided to pay for the repairs out of pocket. I found on multiple reddit and mercedes forums that this is a common issue in Mercedes C class vehicles made on and around 2016. My service advisor told me that he has so many customers from these panoramic sunroofs failing due to a cost cutting measure from Mercedes who decided to use plastic tracks instead of metal. He also informed me that they went back to metal a few years after my car was manufactured. This leads me to believe that Mercedes acknowledged the issue and is trying to hide it from the federal safety agency. Here is a link to a forum post that has a similar picture to how mine looked, notice that one side is stuck in a higher position. [XXX] Here is another post with others with similar issues [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Nov 9, 2023 · Steering · 40,000 miles · CT

The contact owns a 2015 Mercedes-Benz C300. The contact stated that after starting the vehicle, there was an abnormal grinding sound coming from the vehicle. The contact stated that the steering wheel had seized. The contact had the vehicle towed to a certified mechanic and was informed of the federal safety agency Campaign Number: 18V850000 (Steering) and the contact was referred to the dealer. The dealer was contacted and confirmed that the VIN was not included in the recall. The vehicle had not been diagnosed or repaired. The manufacturer was not made aware of the failure. The approximate failure mileage was 40,000.

Filed Oct 14, 2022 · Suspension · MD

The rear suspension frame was rusted, and the suspension rusted off the frame through normal wear and tear (no potholes, incidents, etc). Left side rusted off, Right side is on its way. Brake distance was increased and suddenly braking on the highway resulted in back of car swerving slightly, almost hit a truck that suddenly merged into my lane. This was discovered during an MD state inspection, I called 6 dealerships in the area, and all were familiar with the issue with this chassis. I got two estimates saying the same problem. This forum shows that there are many more like me, and even in the UK dealerships are doing replacement free of charge due to how widespread it is: https://www.benzworld.org/threads/w204-rear-subframes-deterioration.3048088/ The part has not been inspected by the manufacturer/police/insurance inspector. There were no warning lights or any alerts on my dash indicating this issue, I only found out bc I just so happened to need to do an MD state inspection, and I had been hearing a squeaking noise. Also, my brake distance was longer, and my car swerved a little under sudden braking on a dry sunny day.

Filed Sep 26, 2022 · Visibility · 48,000 miles · CT

The contact owns a 2015 Mercedes-Benz C300. The contact stated that when she opened the panoramic roof, she heard a grinding noise and sunroof failed to close as designed. The contact then stated that the panoramic roof failed to open and close as needed. The vehicle was taken to the dealer where it was diagnosed that the panoramic roof guide rail had fractured and needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure and the contact was provided a case number. The failure mileage was approximately 48,000. The VIN was unavailable.

Filed Apr 7, 2022 · Steering, Suspension · VA

I drove over an object on the highway and noticed my car veering left and wobbly when turning. A week after, it is squealing like a load of piglets in my trunk whenever I go over a bump, then my battery light came on and I took it to the shop and contacted my insurance, who denied my claim saying it was 'wear and tear'.

Filed Nov 13, 2021 · Body, Steering · PA

The subframe rotted out causing the lower control arm bracket to detach from the frame. This has caused loss of control of the back left wheel and causes the car to shake and swerve when braking. This exact issue has led to recall in Canada. First noticed due to a squeaking and clunking sound. Later on the same day, I pressed the brakes on the highway and felt the described shaking/swerving. My mechanic has let me know that the car is now un-drivable due to the safety issue this causes. One of the rear subframe’s main purposes is to absorb and disperse impact. Not only have I entirely lost control of the rear left, but any crash that this could have led to could have been significantly more dangerous due to the failed subframe. As stated prior, this exact issue has led to recall in Canada and I believe that it should lead to recall in the USA as well.

Filed Mar 27, 2021 · Driver assistance, Steering · TX

The c300 4matic specifically should be recalled because something near the front end squeaks and makes all types of noises