What 584 owners told NHTSA about the 2012 Mercedes-benz C-class Coupe

The contact owns a 2012 Mercedes-Benz C300. The contact stated that the vehicle was taken to the dealer for a routine maintenance check and she was informed by the dealer that there was a hole in the subframe. The contact was informed that the subframe needed to be replaced. No warning light was illuminated. The vehicle was not repaired. The manufacture was not notified of the failure. The failure mileage was approximately 80,000.

NHTSA ODI 11489862

Rear Subframe Cracking in Mercedes Benz 2012, C- Class, Sports. It can be life threatening for driver and passengers. Cost is $5700 for repairs. This replacement is free in Europe and Canada.

NHTSA ODI 11488998

Rare Subframe breaking off parts are not available for at least 6 months. I have kids and mechanics advise me to keep it off the road. My only means of transportation

NHTSA ODI 11488700

The contact owns a 2012 Mercedes-Benz C300. The contact stated that while having an oil change performed on the vehicle by an independent mechanic, he was informed that the cross member was severely corroded. The contact was informed by the mechanic that the vehicle was unsafe to drive. Neither the dealer nor the manufacturer had been notified of the failure. The vehicle was not repaired. The failure mileage was approximately 125,000.

NHTSA ODI 11487590

The contact owns a 2012 Mercedes-Benz C300. The contact stated that the vehicle was taken to be serviced under an unknown recall however, the mechanic informed him that the rear subframe was severely rusted, creating holes in the subframe. The dealer diagnosed that the subframe needed to be replaced. The vehicle had not been repaired due to the part being on backorder. The manufacturer was made aware of the failure and informed the contact that there was no recall or warranty coverage for the failure. The approximate failure mileage was 65,500.

NHTSA ODI 11485892

- Right Rear Subframe; Yes, available for inspection. - My mechanic told me that driving the car more than 2 miles or at a high rate of speed was very dangerous. He told me there that if the car braked quickly or was driven at a high rate of speed that there was a very good chance of an accident. There is a risk of the right control arm detaching from the frame; this could cause the car to be uncontrollable with the right rear wheel and control arm detaching from the vehicle. - Yes, the issue was confirmed by my mechanic, who works at an independent service center. - No. - There were no warning lamps or messages. I had begun to hear a loud clunking noise, usually when braking.

NHTSA ODI 11484148

I’m filing a complaint due to a concern regarding the rear subframe of my vehicle becoming rotted/rusted out and falling apart at any time. This is due to a Mercedes Benz manufacturing issue where they tried cost cutting which turned out very poor quality materials for this very important assembly. I have researched online about this problem, and turns out, it is very common with this body style c300 ('08 - '14). There are hundreds, if not thousands, of individuals within the USA who are having this exact same issue with as little as 60,000 miles. Most are happening around the 90,000 mile mark however. They primarily mention in many online forums how scared they were when it happened and how lucky they are it didn’t cause a major accident…yet. My car only has ~110,000 miles and is just about 10 years of age. This issue should never happen for a vehicle with such low miles and such a short life, especially from a prominent and distinguished automotive company. This is a Huge Safety Concern, and I am Scared that this subframe will fail without warning and at a high speed, which can likely cause me to be involved in a major accident where people are killed or seriously injured. It is astonishing how this subframe was not recalled by now and how Mercedes USA has not taken responsibility for this. This issue needs to be addressed and recalled Immediately before people are killed or seriously injured, and before more of these parts break. Please look into this very soon as this is a very serious matter.

NHTSA ODI 11483789

The contact owns a 2012 Mercedes-Benz C300. The contact stated that the vehicle was taken in for a routine service check at the dealer and the mechanic informed her that the rear subframe was rusted and the vehicle was unsafe to drive. The contact was informed that the part was on back order. The manufacturer was not contacted. The failure mileage was 119,000.

NHTSA ODI 11483675

the Rear Subrame CRACKED while Driving, Almost causing a Major accident with my son in the car as well. This seems to be a MAJOR problem being overlooked and ignored by Mercedes Benz . This repair is going to Cost me $ 3000-$ 5000 Dollars. and the Replacement Subframe is Impossible to find and on Back order ! so Now I'm without a Vehicle for God knows How long ?? I Feel there is No Doubt this is a Defect and Should be Covered by Mercedes Benz and a Recall ! How is this not being investigated is Really Scary. How can a Frame or a Car just Crack ? That's Not safe for ANYBODY !

NHTSA ODI 11483036

During a routine oil change Mercedes mechanic discovered our rear subframe is rusted on both sides and needs to be replaced. This is apparently a well known problem, and Mercedes will replace this for free in Germany, but has not recalled the subframes in the US. Mercedes created a new OEM part as the replacement part, proving the original part is faulty. However Mercedes does not have enough parts ane every mechanic we have spoken with has several subframes on order for months at a time. We have waited 9 weeks at this point. Many Mercedes drivers subframes have broken making the cars undrivable.

NHTSA ODI 11482722

Dealer states that the rear subframe has rusted and degraded to the point of requiring full replacement. The car is 10 years old with 98,000 miles on the odometer. This is premature degradation of an essential component.

NHTSA ODI 11482359

Took my car in for inspection at the Mercedes dealership. They advised the rear subframe was rotted or rusted. This occurred from the inside. The vehicle is garage kept. They advised Mercedes has no re-call on the issue in the United States. They are covering the issue outside the US. This is a major safety issue.

NHTSA ODI 11481592

The contact owns a 2012 Mercedes-Benz C300. The contact stated that the vehicle was taken to the dealer for an airbag inspection. During the inspection, the dealer informed the contact that the rear subframe was corroded. The vehicle was diagnosed and the contact was informed that the brake lines and rear subframe needed to be replaced. The vehicle was not repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 120,000.

NHTSA ODI 11477748

The contact owns a 2012 Mercedes -Benz C300. The contact stated that upon inspection of the vehicle, he was informed that corrosion had developed on the subframe. The dealer informed him that the subframe needed to be replaced to prevent a possible severe safety failure. The contact emailed the manufacturer about the failure and received a response informing him that they could not offer any assistance. The manufacturer referred him to the NHTSA for additional assistance. The vehicle had yet to be repaired. The failure mileage was approximately 113,000.

NHTSA ODI 11476904

The contact owns a 2012 Mercedes-Benz C300. The contact stated that while her granddaughter was driving the vehicle, there was a rattling sound coming from underneath the vehicle. The vehicle was later inspected by an independent mechanic who diagnosed that the rear passenger’s side wheel well had sustained severe rust and corrosion and informed the contact that the vehicle was unsafe to be driven. The vehicle was not yet repaired. The manufacturer and local dealer were not notified of the failure. The VIN was not available. The failure mileage was 115,000.

NHTSA ODI 11475858

The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving approximately 2 MPH over a speed bump, there was a loud cranking sound coming from the vehicle. There were no warning lights illuminated. The vehicle was taken to the local dealer and diagnosed with failure to the rear subframe due to severe rust. The vehicle was repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 121,218.

NHTSA ODI 11475116

The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving 70 MPH, there was an abnormally loud sound from the rear of the vehicle. The contact lost control of the vehicle. There was no warning light illuminated. The contact was able to continue normal driving once he regained control of the vehicle. The contact scheduled an appointment with an independent mechanic for the vehicle to be inspected. The contact was informed that the rear subframe had detached from the passenger’s side of the vehicle due to severe corrosion. The dealer was notified of the failure and informed him that there were no recalls related to the failure on his vehicle. The manufacturer was not notified of the failure. The vehicle was not repaired. The failure mileage was approximately 138,000.

NHTSA ODI 11467139

The contact owns a 2012 Mercedes-Benz C300. The contact stated that while the vehicle was receiving a routine maintenance, she was informed that the rear sub frame was rusted and had two holes. The vehicle was diagnosed that there was a transmission leak and the rear sub frame needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure but no additional assistance was provided. The failure mileage was approximately 88,000.

NHTSA ODI 11464082

The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving approximately 65-70 MPH, he heard abnormal clicking sounds coming from the rear of the vehicle. Additionally, the contact stated that while driving and depressing the brake pedal to come to a complete stop, the vehicle swerved while stopping. The vehicle was taken to an independent mechanic where it was diagnosed that the rear driver's side subframe was severely corroded and fractured and needed to be replaced. The dealer was notified of the failure and informed the contact that the vehicle would be repaired at his own expense. The vehicle was not repaired. The manufacturer was notified of the failure but did not provide any assistance. The failure mileage was approximately 75,000.

NHTSA ODI 11463118

The contact owns a 2012 Mercedes-Benz C300. The contact stated that while driving at an undisclosed speed, he depressed the brake pedal and the vehicle swerved. Upon inspection, the contact noticed that the rear passenger's side sub-frame was corroded and the stabilizer arm had detached from the sub-frame due to corrosion. The vehicle was taken to an independent mechanic who diagnosed that the sub-frame needed to be replaced. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 100,000.

NHTSA ODI 11456741

Vehicle was in for state inspection at an authorized inspection station. It failed inspection due to severely rusted and deteriorated rear K-Frame which had to be replaced to pass inspection. This is a major defect I feel caused by manufacture negligence. There were no warnings, messages or any signals indicating a problem. This issue could have severely caused an injury or even death had it not been detected by the mechanic inspector. Mechanic stated to me that he had replaced several of the rear K-Frames in the last year on this make and model.

NHTSA ODI 11456652

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.

NHTSA ODI 11455453

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.

NHTSA ODI 11451935

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.

NHTSA ODI 11446590

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.

NHTSA ODI 11443648