2012 Mercedes-Benz C-Class Structure

We are having issues when braking. The backend of the car wiggles when braking hard. Shop advised that the subframe on the passenger side completely broke away and on the driver side it is very rotted. They advised this is a safety issue since the broken side could pierce the gas tank. I googled this and found that there was a warranty extension for the same year and make car (document MC-10233796-0001) Spoke to the service department and they advised this did not apply to our VIN. I called the corporate number on the warranty extension letter and they advised the same. My complaint is that several other Mercedes models and makes have this issues and are covered. Why isn't ours? Based on images I found online it looks to be the exact failure mode. My son was supposed to drive the car 4.5 hours on the 4th and could have gotten into an accident or been stranded. I also read that in Germany they are fixing all vehicles with this issue.

car has a rear subframe damage from corrosion

The contact owns a 2012 Mercedes-Benz C300. The contact stated that the front driver's side interior door handle was fractured. The contact was unable to open the door from inside the vehicle. An independent mechanic inspected the vehicle and referred the contact to the manufacturer for assistance. The dealer was not notified of the failure. The vehicle was not repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline for assistance. The failure mileage was approximately 95,000.

Rear subframe is corroded, rusted through, and cracking.

Recently we had he brakes replaced and new tires put on to prepare for a trip out to Minnesota in a couple of weeks. My son felt like the car wasn’t driving correctly and took it to the shop and upon being put on the lift the service department called and said the rear subframe rusted out and was broken and the gas tank was scratched do to the subframe rubbing against it. When he called Mercedes they told him there was an extended warranty put on these cars which I never received a letter concerning this issue. *The car is waiting to be towed to Mercedes, they would not give us back the keys, it was too dangerous to drive. *my son unknowing drove this car on the highway putting himself and others in danger for who knows how long. If he did not take it in for a check before driving himself and his father to Minnesota they could have been killed. Perhaps a fire due to the gas tank damage. *confirmed by independent repair shop but will be seen when the car is towed to Mercedes. *there was no warning to the dangerous situation my family was placed in. The cars should have been recalled. We were told by Mercedes they were fixing the problem as it arises, luckily no one was injured or killed when this problem arose!

The contact owns a 2012 Mercedes-Benz C300. The contact stated that while driving approximately 55 MPH and pressing the brake pedal, the entire vehicle shifted to the left. Additionally, while driving at various speeds the vehicle was unstable and experienced vibration. The vehicle was taken to an independent mechanic who discovered that the subframe of the vehicle had severe rusting and corrosion and that the vehicle was unsafe to operate. The vehicle was not yet repaired. The local dealer and manufacturer were not notified of the failure. The failure mileage was 95,000.

The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving at various speeds, the rear end of the vehicle was shaking and vibrating abnormally. While the vehicle was in for routine maintenance, it was discovered that the rear subframe was severely rusted. The cause of the failure was not determined. The vehicle was not yet repaired. The manufacturer was not notified of the failure. The failure mileage was 65,000.

The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving 30 MPH, she started hearing an abnormal sound. The contact stated no warning light was illuminated. The contact took the vehicle to the local dealer, where it was diagnosed with needing the rear subframe to be replaced due to severe corrosion. The vehicle was not repaired. The manufacturer had been informed of the failure. The failure mileage was approximately 120,000.

- 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.

The rear subframe rusted and completely cracked. The car started to shake violently while I was on the highway. Fortunately I was in the right hand land and was able to slow down. I was driving in the car with my mother. My understanding from the mechanic is that we were lucky not to be killed or hurt anyone else. The frame is completely cracked. I called the local dealership and they said this is an extremely common problem. So common they have multiple vehicles on the lot waiting for parts, and the waitlist is indefinite. There were absolutely no warnings on the car.

I have a 20212 Mercedes C300 with 70,000 miles. I took it into the MB dealership for inspection and was told that the rear subframe was rusted through. The subframe's failure also caused the brake lines to rust to the point of needing to be replaced. The subframe repair will cost $5,900 and the brake line replacement will cost around $1,200. The dealer told me the car couldn't be driven safely, so I had to leave it there to be repaired. There were no interior warning alarms about the structure or the brakes. According to forums on Benzworld.org, this is a known problem on these specific cars and the component is replaced for free by MB in Europe.

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.

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.

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.

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.

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.

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.

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 contact owns a 2012 Mercedes Benz C300. The contact stated that while driving 45 MPH, the contact started to lose control of the vehicle while depressing the brake pedal. There was no warning light illuminated. The contact regained control of the vehicle and drove to a dealer. The vehicle was inspected, and the mechanic discovered that the subframe had fractured due to severe corrosion. The contact was notified that the vehicle was unsafe to drive. The contact was provided an estimate for the repair. The manufacturer was also notified of the failure and informed her that 15% of the cost of the repair would be covered. The vehicle was not repaired. The failure mileage was approximately 62,000. The contact stated that their vehicle was finally repaired by the dealer in Dec. 2022. The manufacturer helped pay approximately 13% of the total repair costs.

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 !

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.

As per an inspection by my mechanic, the rear sub frame of the vehicle has cracked due to rust corrosion and subsequent metal failure. I first noticed the issue when there was a thumping sound over bumps and the car started to swerve when applying brakes on the highway, quite a scary situation as I thought the brakes were failing. The car has 78000 miles and has had all maintenance done. The is no other rust on or underneath the car. According to my research on Mercedes-Benz owner forums I discovered that it is a common issue and that, so far, Mercedes Benz has not issued a recall in the US. According to these forums Mercedes has issued recalls in other countries (although I have not confirmed this point). The estimated cost to replace the sub frame is $3000 including labor and there is an 8 to 10 week backlog for the part due to the number of failures occurring. In the meantime I cannot drive the vehicle as my mechanic has told me that the car is not safe to operate.

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.

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.

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.