Which parts fail
Components named in complaints (doors, hood, frame, rust, paint and trim).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2009 Mercedes-Benz C300 owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2009 Mercedes-Benz C300. The contact stated while driving approximately 60-70 mph, the vehicle started shuddering and lost stability. There were no warning lights illuminated. The contact stated that as she disengaged the accelerator pedal, the vehicle stopped shuddering. The vehicle was taken to an independent mechanic who diagnosed that the rear subframe was rusted and had fractured into two pieces on both sides of the vehicle, and the lower control arms were hitting the gas tank. The check engine warning light and TPMS warning light were illuminated at the time of the diagnosis. The manufacturer was not made aware of the failure. The vehicle was not repaired. The approximate failure mileage was 120,000.
The contact owns a 2009 Mercedes-Benz C300. The contact stated while driving 70 MPH, he heard an abnormal clunking sound coming from the rear of the vehicle. The contact veered to the side of the road. After looking under the vehicle, the contact noticed that the subframe located next to the gas tank was fractured. The vehicle was taken to an independent mechanic where it was diagnosed that the rear subframe had fractured from the weld point. However, the parts to do the repair were not available. The vehicle was not repaired. The dealer was not notified of the failure. The manufacturer was notified of the failure and referred the contact to the dealer. The failure mileage was approximately 190,000.
The contact's son owns a 2009 Mercedes-Benz C300. The contact stated upon taking the vehicle to the dealer for servicing, he was informed that the subframe was severely rusted. The contact stated that his son then informed him that while he was driving approximately 50 MPH and depressing the brake pedal to come to a complete stop, the vehicle started wobbling significantly. The dealer replaced the subframe, the rear tires, and completed an alignment on the vehicle. The vehicle was repaired. The manufacturer was notified of the failure and referred the contact to the NHTSA. The failure mileage was approximately 87,000. Vehicle has been repaired.
The contact owns a 2009 Mercedes-Benz C300. The contact stated while driving at various speeds, the vehicle would sway from side to side as an abnormal clonking noise would emit from the vehicle without warning. The vehicle was taken to an independent mechanic where they discovered that the subframe had cracked due to severe corrosion. The dealer was contacted about the failure, and she was given an estimate for the repair. The manufacturer was also notified of the failure and the contact was given a case number. The vehicle had yet to be repaired. The failure mileage was 94,200.
The contact owns a 2009 Mercedes-Benz C300. The contact stated that while her husband was driving at an undisclosed speed, the vehicle swayed on the roadway. The vehicle was taken to an independent mechanic who diagnosed that the rear subframe was corroded and needed to be replaced. The mechanic contacted the dealer to order the replacement part and was informed by the dealer that there was a recall for the subframe; however, the VIN was not included. The vehicle was not repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 70,000.
The contact owns a 2009 Mercedes-Benz C300. The contact stated that while driving at various speeds, the rear end of the vehicle would fishtail and become extremely unstable while driving over a bump in the road or while turning. Upon inspection, the contact discovered that the subframe was severely rusted. The cause of the failure was not determined, and the vehicle was not yet repaired. The local dealer was notified of the failure. The manufacturer was not contacted. The failure mileage was 201,000.
The contact owns a 2009 Mercedes-Benz C300. The contact stated while driving at various speeds, the driver's side rear tire inverted into the wheel well due to excessive corrosion. The contact had taken the vehicle to an independent mechanic where he confirmed the failure and informed him that the subframe needed to be replaced. The manufacturer had yet to be notified of the failure. The vehicle had yet to be repaired. The failure mileage was 130,000.
the rear subframe @lower control arms right side rust on bracket when put break on the car go to right and make noise!!! the car just have 83.000 miles!! this have re call or not?we d'ont know untill seaching on web side findown couple owner C300 have problem said some
I bought this car for my 18 year old son based on Mercedes reputation for safety and longevity, only to discover that Mercedes has a widely acknowledged issue with rotted sub-frames -- it's a serious safety issue and recalled in other countries. My son was was driving on the highway and the tire exploded. He was so close to being killed because the car went out of control. After getting it towed to my mechanic, he advised me that alignment adjusters were stuck, the subframe was rotted, the lower control arm subframe mounts were broken from the subframe and they were hitting the gas tank. Luckily, the tire only exploded as oppose to the entire vehicle bursting in flames. There were no warning lights or messages, only the feeling that the tires needed to be aligned. We bought new tires and were told an alignment was done from Town Fair Tires, which was untrue. …
My spouse was driving approx 40MPH. Traffic light turned amber so she applied the brakes, at that point the vehicle pulled violently to the left into on coming traffic and at the same time the vehicle rear end was fish tailing out of control.Our mechanc inspected the vehicle and discovered the rear sub frame assembly had cracked on the driver side. We were advised by the mechanic this car is un driveable. Our Insurance appraiser inspected the vehicle and stated this is very common with this model vehicle and is a very bad design flaw. I contacted the Mercedes dealership and they advised there is no re-call on the subframe so I would need to pay $4000-$5000 for the repair. This vehicle is worthless to me now and is a grave safety risk to drive. I do not have the funds to fix this vehicle so I am now without a car. Mercedes customer care will not even answer any telephone calls. …
Body complaints in other C300 years
Frequently asked questions
How common are body problems on the 2009 Mercedes-Benz C300?
NHTSA has 27 complaints about the body & structure of the 2009 Mercedes-Benz C300, 5% of the model year's 576 complaints. The component named most often is body (17 mentions).
Is there a recall for 2009 Mercedes-Benz C300 body problems?
No. NHTSA lists no body & structure recall for the 2009 Mercedes-Benz C300, though it has 8 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2009 Mercedes-Benz C300 body problems start?
Half of the complaints with a recorded mileage happened before about 94,000 miles.
Is it dangerous?
Owners linked 1 crash, 0 fires and 1 injury to body & structure problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.