2012 Mercedes-Benz C 300 Body & structure Problems

Mercedes of Danbury replaced the rear sub frame CODE 3441 47, since my mechanic (Newtown Auto Repair) told me that the Front subframe is in real bad shape, rotten/rusted, that it is dangerous to drive the car in this condition since the wheel and steering components are part and attached to it, the car would be out of control and all over the road any of these components fail and pull / brake away from the rusted out Sub Frame. When I brought the car in was under the impression that Mercedes Benz would replace front and back Sub Frames. But now they informed me of only recall on rear subframe, rear subframe will let go wheels will collapse, front controls the car and failing could kill people and total the car. frames.

NHTSA ID

11701264

Incident

Nov 20, 2025

Rear subframe rotted out and broke due to corrosion. Rear crossmember is broken and needs replaced. My safety as well as the safely of other was put at risk. Loss of control at high speed could have been deadly. Luckily, I wasn’t going very fast at the time of incident or else who knows what would have happened to me or bystanders. Independent service center inspected and confirmed that incident was due to corrosion in the rear. They informed me of the extended warranty (20 years, unlimited miles) on 2008-2015 C300 models for this particular issue as my safety and the safety of others was put at risk. There were some symptoms leading up to the incident. At the time of braking the car would become unstable and feel skittish in the rear. It felt as if the rear was sliding to one side. The vehicle would also make some metal clinking noises at sharper turns. The symptoms had been more frequent in the prior 2-3 months of incident. The vehicle has been inspected and diagnosed by one shop and is currently getting a second opinion from another independent service center.

NHTSA ID

11682005

Incident

Jul 27, 2025

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.

NHTSA ID

11600131

Incident

Jul 3, 2024

Took my car for a doorknob repair and was told the whole subframe is rotted. They told me not to drive the car on the highway. The car brakes very hard to the right and always goes right while making cranking noises. Car feels very unsafe. I paid a lot of money for this and own a 2012 c300 4matic.

NHTSA ID

11592433

Incident

May 28, 2024

This is a low mileage car with odometer reading of 25668 (less than 2000 miles per year), used sparingly and always parked in the garage. On 05/07/2024 I noticed brake fluid flowing from the left rear side of the car; on examination this seemed to come from the flexible hose that connects the brake fluid line to the brake caliper. I called my Mercedes-Benz (MB) dealer and arranged for further inspection and service. The technician identified that the brake fluid lines to the rear were both totally corroded and in need of immediate replacement. Since the lines were embedded behind the subframe it necissated lowering the subframe to access. Other parts were also severely corroded and required replacement. (see attached PDF of Invoice) The total cost of the repair was $4,592.93. The dealership applied a discount of $150.00 to this for an amount due of $4,442.93. As an engineer, I believe the material used for the brake fluid lines were unsuitable and furthermore were unprotected for the harsh environment experienced under the car, and I believe MB with all their experience in automobiles manufacturing over the years clearly should have known and forseen this fact; I do believe that MB is responsible for this premature failure of the brake lines of my car aven driven only 25,666 miles to date. I am therefore requesting NHTSA to require MB to reimburse me for the unnecessary expense of the costly repairs. It is only fortunate that this failure was identified in my garage and not on the highway. Please advise me of your resolution. Thank you.

NHTSA ID

11589443

Incident

May 7, 2024

The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving at an undisclosed speed, he heard an abnormal sound coming from the rear of the vehicle, prompting him to pull to the shoulder of the roadway. After a visual inspection, the contact observed that both trailing arms had become detached. No warning lights were illuminated. The vehicle was taken to an independent mechanic, who determined that extensive frame corrosion had caused both trailing arms to detach. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 143,000.

NHTSA ID

11587466

Incident

May 7, 2024

Mileage

143,000 mi

car has a rear subframe damage from corrosion

NHTSA ID

11574257

Incident

Feb 15, 2024

Rear subframe is corroded, rusted through, and cracking.

NHTSA ID

11541080

Incident

Aug 28, 2023

The contact owns a 2012 Mercedes-Benz C300. The contact stated that the vehicle was making a loud bang sound towards the rear of the vehicle while driving over bumps in the roadway. The contact took the vehicle to the dealer and was informed that the rear subframe and the rear brake line were severely rusted. The subframe was replaced under an extended warranty coverage; however, the brake line was not covered under the extended warranty. The brake line was not replaced. The manufacturer was made aware of the failure. The approximate failure mileage was 110,000.

NHTSA ID

11533167

Incident

Jun 21, 2023

Mileage

110,000 mi

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!

NHTSA ID

11528670

Incident

Jun 19, 2023

The contact owns a 2012 Mercedes-Benz C300. The contact stated that while his wife was driving at an undisclosed speed, she heard an abnormal sound coming from the rear of the vehicle. The vehicle was taken to an independent mechanic where it was diagnosed that the subframe wheel assembly needed to be replaced. No warning lights were illuminated. The vehicle was repaired; however, the contact stated that he received an unknown manufacturer’s recall for the subframe assembly which it was then taken to the dealer, and the contact was informed by the technician that the rear brake line was leaking and needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure and the contact was informed that the VIN was not included in a recall. The failure mileage was approximately 120,000.

NHTSA ID

11521006

Incident

May 2, 2023

Mileage

120,000 mi

The subframe assembly on my car is defective, as I learned today from my mechanic. This issue is known for my model of car and widely reported online. The mechanic says they have seen this issue before. I heard a strange noise while driving so I took the car to the shop after 60 days of enduring the sound. The shop immediately deemed the car unfit for driving and unsafe. In their words, if I had hit one bad pothole, the wheels could have come off the back of my car, and my gas tank could have been punctured, leading to a potentially catastrophic accident. I am lucky to have gotten this defective part identified before being injured, and others need to be protected from this outcome before a serious injury occurs. As of now this has only been inspected by the shop doing the fix. People online have indicated that Mercedes will not fix the problem free of charge - and in fact they charge a premium to other places to replace this faulty subframe. There were zero warning indicators of this dangerous issue - the car drove completely normally aside from an infrequent knocking sound that would occur every 5-10 minutes under normal city driving conditions.

NHTSA ID

11509955

Incident

Jan 16, 2023

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.

NHTSA ID

11509340

Incident

Feb 6, 2023

Mileage

95,000 mi

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.

NHTSA ID

11505118

Incident

Feb 2, 2021

Mileage

65,000 mi

Cradle and subframe are completely rusted out. This a widely common issue with these cars and am reading it across several forums. Other c300 owners say they have had the exact same issue and request for the MB dealership to fix it. Instead they are given a quote of nearly $10,000 to fix it. MB is responsible for this.

NHTSA ID

11502013

Incident

Jan 15, 2023

Sub Frame broke from rust. Mercedes Benz has acknowledged the issue in Europe and repaired/replaced the part at no charge. Numerous problems and complaints can be found on line indicating that we, the car owner must and can complain to Mercedes for partial or complete support on the repair. But they do not acknowledge the problem in the US.

NHTSA ID

11499206

Incident

Nov 20, 2022

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.

NHTSA ID

11498631

Incident

Dec 18, 2022

Mileage

120,000 mi

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.

NHTSA ID

11496239

Incident

Nov 1, 2022

Mileage

62,000 mi

The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving 35 MPH, the contact heard an unusual noise coming from the rear of the vehicle. The vehicle was taken to the dealer, and the mechanic stated that the rear subframe was rusted and the passenger’s side rear control arm was detached from the subframe. The vehicle was repaired. The manufacturer was contacted and stated there was no recall for the failure. No other assistance was offered. The failure mileage was 43,960.

NHTSA ID

11492564

Incident

Oct 7, 2022

Mileage

43,960 mi

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.

NHTSA ID

11492253

Incident

Nov 4, 2022

The contact owns a 2012 Mercedes-Benz C300. The contact stated that upon taking his vehicle to a dealer for maintenance repairs; he was provided an estimate for the repair of corrosion to the rear subframe of the vehicle. Upon investigation, the contact discovered that the failure could lead to a potential braking system failure. The manufacturer was notified of the failure and informed him that there were no recalls on the vehicle. The vehicle was not repaired. The failure mileage was approximately 97,000.

NHTSA ID

11491578

Incident

Jul 1, 2022

Mileage

97,000 mi

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.

NHTSA ID

11491215

Incident

Oct 20, 2022

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.

NHTSA ID

11491185

Incident

Oct 26, 2022

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 ID

11489862

Incident

Oct 4, 2022

Mileage

80,000 mi

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 ID

11488998

Incident

Oct 12, 2022