NHTSA Owner Complaint Log
This page lists owner-reported complaints filed with NHTSA for the 2012 Mercedes-Benz C-Class. Complaints are unverified consumer reports submitted to NHTSA and do not by themselves prove a defect or defect rate.
Data synced from NHTSA on May 4, 2026
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.
on 6/20/23 I was driving this vehicle on the 5 freeway north bound exit 102 in Washington. i found myself travelling at 60mph just moving over to the middle lane of traffic. i needed to slow the vehicle a little and pushing down on brakes I found there was no reaction from the braking system. Making a quick decision I moved over to the emergency lane where I came to a stop. There were no warning signs of the issue. I had the vehicle towed to my Mercedes Benz dealership where I had the car service the day before on 6/19/23 where nothing was noted on this problem. After inspection from the technician at the dealership it was found that the brake vacuum pump was no longer working. Which technician said had caused the issue and he had never experienced this issue before. i am bringing this to your attention due to it could have caused a fatal accident to with me and other people on the freeway.
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 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.
The drivers door handle broke. In researching online, this has been an issue with Mercedes Benz since they are made of weak plastic. Apparently, they have a more stronger version now. It’s a safety concern as you cannot open the door from the inside.You have to roll down the window, and open the door using the outside handle. What if the power window didn’t work?This is a severe safety concern. If you have to exit the vehicle in a hurry, due to a fire, or accidentally started submerging in water. This should be a recall, we should not have to pay for a replacement to the newer door handle
The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving at various speeds, extra brake travel time was needed to stop the vehicle. There was no warning light illuminated. The contact had taken the vehicle to an independent mechanic where the vehicle was purchased, and he was informed that the failure was caused by the new brake pads placed on the vehicle. The contact eventually took the vehicle to a dealer and was informed that the fuel tank and brake lines were corroded; and the contact was provided an estimate for the repair. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 96,000.
The rear subframe rusted prematurely and broke off important mounts for the suspension and steering. I was driving and had to hard brake. This cause the back end of the car to swerve and almost lose control. I then heard a knocking sound when I pressed the brakes, prompting me to take it into the shop. There I was informed the the subframe was rusted and the vehicle wasn’t safe to drive. I filed a claim with my insurance, but they said it’s wear and tear.
I found out about the Mercedes Subframe failure issue after having problems on the road, that could have killed me, and being warned not to drive anymore by an authorized repair shop because my vehicle was not safe for me to drive. This has caused many other issues with my cars mechanics due to this defect from the Mercedes factory.
I was driving on the freeway and had to hard brake due to unexpected stopped traffic. When I braked the vehicle veered hard to the left and almost lost complete control of the car and nearly caused a serious accident. I drove immediately to a local MB dealer and they confirmed what I was afraid and suspected which was the right rear subframe needs replaced. This car was recently sold to me by a dealer less than a month ago and not a single warning light or indicator warning me of this issue. The repair is over 7500 and the shop highly recommended I no longer drive until it’s replaced. This problem is very common and MB actually covers the cost in Europe and Canada.
Popping sounds and smoke from center dash and right rear speaker. Center speaker magnet extremely hot to the touch.
The left rear weld of the subframe on my 2012 C300 4matic has rotted through and appears to be a manufacture's part defect. I found out about this issue from a brake inspection and told it is a safety concern, which Mercedes Benzes is aware of but has no recalls for the defect.
My car’s left side rear subframe is cracked due to corrosion. I started hearing a weird noise a week ago, and my car suddenly veered to the left side when I pressed the brake. I almost crashed my car because the car moved to the left of the yellow line on the road. I searched about this issue on Google and found that many C-Class owners (W204 generation) are experiencing the same issue due to the design flaws/defects by Mercedes-Benz. Now I have to pay up to $10,000 for the repair that is due to a defective part. In other countries like the UK and South Korea, this issue is covered by Mercedes-Benz, but in the United States, it is not covered. The repair is done at owner’s expense. I fear driving now because my car steers to the left when I press the brake. The rear subframe must be recalled since this issue is now common to all C-Class models produced in 2008-2014, and if car accidents occur, many people can be killed. I almost crashed my car due to my rotten subframe. Please help.
The contact owns a 2014 Mercedes-Benz C250. The contact stated while driving 70 MPH, there was an abnormal frequency sound coming from the speakers followed by a popping sound. The contact then began to smell a burning electrical wiring odor with white smoke coming from the middle dashboard speaker. The contact immediately pulled over and turned off the vehicle. There was no warning light illuminated. Due to the failure, the contact called her father who towed the vehicle to her home where it remained in her possession. The contact reached out to the manufacturer by email and was informed that there were no recalls on the VIN. The contact was then referred to the NHTSA for further assistance. The vehicle was not repaired. The failure mileage was approximately 305,000.
My vehicle has 70,000 miles. always kept garaged. Told by dealer when taken for the yearly checkup that the rear subframe of the car is totally rotted. Needs replacement. Price $3790. Mercedes would only cover 20% of the cost. There have been recalls in Canada with the same issues. Please investigate as this is a serious defect problem and not a warranty issue as Mercedes is claiming.
The contact owns a 2012 Mercedes-Benz C250. The contact stated that she noticed that the air bag warning light was illuminated. The dealer was contacted because the vehicle had been serviced under NHTSA Campaign Number: 21V638000 (Air Bags) and the dealer stated that the seat belt was malfunctioning. The vehicle was not repaired. The manufacturer was contacted, and a case was filed. The failure mileage was 78,000.
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.
A problem with the rear subframe had occurred in which it had started to rust. Due to the severity of the issue I noticed my car started veering when hitting the brakes as well multiple concerning sounds and stability issues with the vehicle. Mercedes has not contacted me about replacing the part nor has their been any warning lights or any indication of the issue being present other than when the subframe had already been rotted. When speaking to MB about the issue their was nothing they could do for me which is questionable being that the cause of this is a manufacturing issue. I have yet to receive any information as to how the issue may be resolved. Not only does this put myself at my family at risk but as well as the community around me. Wether when braking my vehicle may veer and cause a collision or an issue where the subframe fails and causes an accident.
The left side of rear subframe has rusted out. The right side had been repaired by welding by a previous owner. The damage is still present and can be inspected. The broken bracket is right next to the gas tank and can possibly contact or dent the tank during a hard break or collision. This is a common problem with many people expressing this online and at the 3rd party repair shops. No warning signs were present until the bracket snapped. Extensive rust and corrosion around the area, specifically on the inside of the subframe.
It is a wide-spread issue and commonly known issue that when the car battery is replaced in Mercedes-Benz vehicles, the climate control stops working, as well as the blower. The safety issues: •Car battery needed to be replaced during non-daylight hours during the winter. •Climate control stopped working immediately upon battery replacement, and issues with blower arose. •I drove home in the dark, during winter, without the ability to defrost my windows. A quick Google search for this issue will uncover an abundance of consumer complaints and common themes regarding this issue.
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.
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.
The contact owns a 2012 Mercedes-Benz C250. The contact stated while starting the vehicle, the vehicle started very rough with a rattling sound coming from the vehicle. The check engine warning light illuminated. The vehicle was not diagnosed. On another occasion, while opening the front driver’s side door, the door handle fractured. The vehicle was not diagnosed or repaired. The manufacturer was not contacted. The failure mileage was 90,000.
Issue with my rear sub frame rotting out due to rust almost causing a very bad accident in a hard braking situation
The contact owns a 2012 Mercedes-Benz C300. The contact stated that while parked, the vehicle failed to start. The vehicle was towed to the dealer where it was diagnosed as having water intrusion. The vehicle was not repaired. The contact referenced the failure to NHTSA Campaign Number: 22V955000 (Fuel System, Gasoline, Fuel System, Diesel). The manufacturer was made aware of the failure. The failure mileage was approximately 109,000.
During planned car service my mechanics discovered that rear subframe is broken and is not safe to drive anymore. After investigation I found that this is a major issue that Mercedes owners have with this particular model. In Europe for this issue has been issued Recall, however in US for some reason Mercedes don't take responsibility. This is a major Safety hazard with possible fatal consequences.
My vehicle had started swerving when I had hit the brake. I noticed that my rear subframe had been rotting and did more research only to find that this was a common problem amongst Mercedes Benz owners. This is a huge safety issue as not only does it put my cars entire suspension at risk and cause a life threatening accident to me or others on the road it is also very concerning when my vehicle creaks and makes constant noises when driving. There are times it feels as if my vehicle’s suspension will fall out from under it and has been a clear issue Mercedes is aware of yet I have not received any recall notice nor have I gotten any answer as to how Mercedes can help me fix an issue they continuously overlook and sweep under the rug. I fear that eventually something will happen and have been trying to get an answer as to how to get my vehicle repaired without it coming back on me since the root of the issue lies in MBUSA parts snd not on my own doing.
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.
The sub frame broke in half and the dealership said it is due to rust. The car has been garage kept and not driven much at all. It’s a 10 year old car with only about 55,000 miles on it. It’s been used very gently.
I was driving our Mercedes Benz C300 and noticed the braking distance taking longer than normal. Also, the rear end responding differently than normal. We took our Mercedes C300 to Mercedes Benz Dealer to be serviced. The technician looked under the car and found the rear subframe rotted out. The service advisor informed us of this being a known defect. We have to be cautious about driving the car until it's repaired due to the fact of being a serious safety issue. MB needs to recall these vehicles and repair them before someone is seriously injured in an accident. Many drivers are uware their subframe has rotted out. I've taken this car to the same MB shop for 8 years and all in a sudden this comes out of nowhere.
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.
I purchased a 2012 Mercedes C300 AWD from a local dealer and have had it serviced annually. Last week I took it in for the annual servicing and was told by the dealer that the rear subframe had corrosion /rust and the car was not safe to drive. I asked if it was covered under a recall and they said not by Mercedes at this time.They provided a repair estimate that is quite high and close to the appraised value of the car. I asked if there were any options available through Mercedes or the dealer and they confirmed not at this time. I have read many articles related to this problem and imagine there are many complaints on file at NHTSA. This is obviously a serious safety issue and currently Mercedes is not taking responsibility and directing the costs to their customers. In addition there is a subframe parts shortage and it could take weeks to fix. I'm requesting that this be listed as a recall item by Mercedes.
Applied brakes coming down a slight grade and vehicle made a clunking noise and became unstable. Pulled and pitched as brakes were applied and released. Upon checking brakes it was very visible that the rear subframe had failed on the right side and the left was severely compromised. I hard braking situation would have resulted in a crash… The severe damage was not visible a week ago until it rotted out from the inside and failed under load.
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 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.
Rear Sub Frame Assembly failure. It is available for inspection upon request. Vehicle rear end begins to wobble at speeds above 40 mph. The issue causes steering to become more complicated and the vehicle veers sharply while braking. This issue makes all C Class vehicles with this Sub Frame Assembly extremely unsafe, especially at highway speeds. Vehicle has been inspected by the authorized Mercedes Benz dealership in Indianapolis, IN. Service Advisor stated it's "amazing" that there hasn't been a recall issued yet. Based on this body style there have been roughly 320,000 of these C-Class vehicles sold. If the NHTSA truly cares about safety, they will launch an investigation into this matter. There are no warning lamps or messages that appear prior to this failure.
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 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.
This issue concerns rear Sub Frame corrosion. My car has always been serviced at the Mercedes Benz dealer where it was purchased as recommended. Upon recievieing my car after a service I was informed that the subframe in my car was badly damaged by metal corrosion. In fact I was told that the car was unsafe and should not be driven as total failure would likely cause lose of control of the vehicle. I was offered a repair quote in excess of $5,000 to replace the rotten subframe. I have since found that this failure is common the the model and many cases have been reported. In Europe and Canada recalls have been issued. Cases in the US are apparently felt with on a "case by case" basis. I see this as a serious safety concern for our highways. Failure is common from reports and and serious accidents surely possible. I have removed my car from service, but many are being driven right now. Mercedes Benz is aware of this and is doing nothing to date to take responsibility for this design/construction defect. I add my voice to the many that I hope have contacted you with concern.
I went to my dealership for a routine yearly service appointment, which I do regularly, along with yearly inspections. My car was purchased new to my liking in 2012 with input from my late partner who passed before I received it! I waited quite some time to get my gem. When it arrived, I had all I could do to drive it, given my loss. I garage it every day for the last 10+ years, never left it outside, it is pristine, only has 64,000 miles on it. To my disbelief, was informed by the MB technician yesterday that I have corrosion on my left rear sub panel, and that I should not drive it and consider a trade-in - NO WAY!! And that the part would cost me over $4,800 to replace and it would not be available until February 2023. So, I should drive another car, which I do not have!!!!! After researching, I am beyond disappointed that this is a known MB manufacturer's defect that has gone this far, customer action needs to be taken!!! My local car dealership states they knew nothing about this, however; pointed out a number of Mercedes C300 in their parking lot sitting with the same life-threatening issue. They were eager for me to talk to sales for a trade-in. Go figure this strategy, NOT. I have had three Mercedes Benz which I love, I do not want to part with this gem, but my need to . . . Please do something . . . Safety and Life matters
Faulty camshaft adjusters creating timing chain to stretch and tensioners to fail , causing excessive wear to the crankshaft and wear of the teeth resulting in catastrophic damage and complete engine failure ( I have not replaced this timing chain or camshaft adjuster yet but i can hear the timing chain rattling from the defective parts from manufacturer. )
The contact owns a 2012 Mercedes-Benz C300. The contact stated that upon parking the vehicle at the dealer parking lot, she heard abnormal sounds coming from the rear of the vehicle. There was no warning light illuminated. The dealer diagnosed that the rear subframe was severely corroded and the rear control arm was detaching from the subframe. The dealer diagnosed that the subframe needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA Hotline. The failure mileage was approximately 79,000. The contact was informed by the service advisor that the vehicle should not be driven until it is repaired due to the extensive damage to the subframe.
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.
Corroded rear cradle driver side. Causing instability driving. Cradle on back order for months according to local Mercedes parts department
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.
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.
My Mercedes 2012 C 300 is leaking gas which may lead to fire ( the fuel filter flange when operated in high temperatures
Car is leaking gas very dangers . I contact Mercedes dealer regarding the recall on this type of Mercedes i have and they said only vehicles manufactured from April 18, 2011, through July 12, 2011. Mine was before or after , and they refuse to give me the exactly date for my car manufacturer. Car I use for Uber , and i don’t have any other income . If someone just through away a cigarette in parking lot might cause a big problem in the building and others cars in parking
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.
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
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.