2015 Mercedes-Benz C-Class

The R&R rear subframe is showing premature corrosion that can cause structural failure. This can lead to rear suspension detachment, erratic driving behavior, and severe safety risks. This problem has been confirmed by the Mercedes Benz dealer. This has been inspected by the Mercedes Benz dealership. There were no warning lamps, messages or other symptoms of the problem prior me finding out it was failing. I had a multi inspection performed on my car due to another issues and the MB service dept found it during that time. Which means if I had never had the multi inspection done due to another issue I was having with the car, I would not have known.

Rear subframe has rust and holes. Dealer is saying not covered under warranty and asking for 8000

REAR SUBFRAME RUSTED OUT AND BROKEN

The rear subframe completely rusted out on both sides causing the car to swerve very dangerously to the left when braking. The subframe was diagnosed by the dealer. There was a " collision prevention assist inoperative" warning a week prior the the car noticeably swerving when braking

Fuel pressure pump hose on top of the engine leaks gasoline this is a serious safety concern the hot engine can catch fire easily, I noticed due intoxicating vapors in cabin while driving because car takes air from q side of the engine to the cabin. The car only has 28k miles on it.

Exhaust camshaft pulse wheel shifted on camshaft. Replacement of camshaft, positioner, oil control valve, timing chain and chain tension was recommended.

After strong fuel odor in interior of car, inspected the engine and discovered fuel in the top of the engine this is a serious safety concern due possible car fire. The leak appear to be due failure of a top engine gasoline hose due low quality. The car barely has 30k miles .

The contact owns a 2015 Mercedes-Benz C300. While driving approximately 15 MPH, the brake pedal was depressed, and the body of the vehicle shifted to one side. The vehicle was drivable after the failure. There was no warning light illuminated. The vehicle was driven to the residence and parked. The contact stated that due to the failure, the vehicle was unsafe to drive. An independent mechanic was contacted, and it was determined that the rear subframe was corroded. The vehicle was not repaired. The manufacturer was notified of the failure, and it was confirmed that the VIN was not under recall. The failure mileage was not available.

When buying this car from Auto Shoppers, they was an airbag light on but dealership said it was a sensor from auto detail on car or recall. Got diagnostic from Mercedes Benz, findings was there was no air bag in place on drivers side. Dealership did not tell us there was no air bag and only was a sensory/recall and are refusing to fix it.

I am reporting a structural failure of the rear subframe due to corrosion on my 2015 Mercedes-Benz C300 4MATIC. The failure was diagnosed by an authorized Mercedes-Benz dealer, who confirmed that the rear subframe has corroded and broken, compromising the structural integrity of the vehicle. This is not cosmetic rust. The subframe is a load-bearing structural component, and its failure creates a serious safety risk, including potential loss of vehicle control. I have been advised that the vehicle may be unsafe to operate in its current condition. The vehicle has approximately 143,000 miles and has been registered and operated in Connecticut, a salt-use state. However, this level of corrosion leading to structural failure of a major suspension component is premature and not consistent with normal wear and tear, even in such environments. I contacted Mercedes-Benz USA and escalated the matter to an Executive Referral Manager. Mercedes-Benz acknowledged the seriousness of the issue but declined to provide any repair assistance, stating that my vehicle falls outside of warranty extension and goodwill parameters. Mercedes-Benz did not dispute the nature of the failure or its safety implications, but refused to address the issue based solely on internal policy criteria such as age and mileage. A rear subframe supports critical suspension components. Corrosion leading to structural breakage can result in instability, misalignment, or failure of suspension components while driving, increasing the risk of a crash. This issue appears to be consistent with known reports of rear subframe corrosion in similar Mercedes-Benz vehicles, raising concern about a broader safety defect. The failure was identified during inspection, and repair costs are estimated at approximately 5,000–6,000. I am submitting this complaint due to the safety risk posed by structural failure and the manufacturer’s refusal to address the issue.

Strong gas odor coming from vent when heat and AC is on. Odor was causing dizziness and had to drive with window open or vent off. When opening the hood gas odor was also present. Brought to the mechanic and found fuel lines leaking. Went online and found out this is a very coming problem. I had to spend $657. to repair. Mechanic stated Mercedes issued a service bulletin but not a recall.

1. What component or system failed or malfunctioned? The low-pressure fuel feed line (Part No. 274-070-35-00) and its associated clamps connected to the high-pressure fuel pump. Availability: State: The defective hose is currently on the vehicle and is available for inspection. If the repair proceeds, I request the dealership to retain the failed part for my inspection. 2. How was your safety or the safety of others put at risk? The failure resulted in raw fuel leaking directly into the engine compartment. This creates an immediate and severe fire hazard, as gasoline is being released near high-temperature engine components. Furthermore, the strong odor of gasoline entered the cabin through the HVAC vents, exposing passengers to toxic fuel vapors while the vehicle was in operation. 3. Has the problem been reproduced or confirmed? Yes. The defect was confirmed by Mercedes-Benz of Orange Park (Dealer Code: 64111). The technician performed a 'cold start' inspection and verified fuel leaking from the low-pressure line to the high-pressure pump. > Note: My service advisor's admitted: Yes sir we will do the hose. 4. Has it been inspected by the manufacturer, police, insurance, or others? Answer: The vehicle has been inspected and the failure documented by an authorized Mercedes-Benz dealership technician. It has not yet been inspected by insurance or police as no fire has occurred yet; however, the dealership has identified the part as defective. 5. Were there any warning lamps or other symptoms prior to failure? There were no warning lamps or dashboard messages. The primary symptom was a pungent smell of raw gasoline inside and outside the vehicle, specifically during cold starts. These symptoms first appeared recently [January 3rd, 2026] and became persistent as ambient temperatures dropped.

I have been informed by my dealer's service unit that the rear subframe of my car (2015 Mercedes C class) is rusted with holes. My understanding is that this can affect the integrity of the structure and cause problems while driving. According to your website [XXX] ) , this should be covered under a warranty extension. However, Mercedes says that my car is not, and to fill out this form if I believe it should be. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

I took my car for service and they found a rusted rear subframe, with a small hole in it. I was informed that the car was not safe for my annual trip from NJ to FL (about 1000 miles). I was also told that this defect was a recall for cars through 2014. My car is a 2015 and I have the same defective part - which is supposed to be manufactured with rustproof material. I am requesting that this car be recalled and the part replaced by the manufacturer.

Purchased this car in September 2024 for our [XXX] son. Upon inspection at our local Mercedes Dealership on December 1, 2025, we were informed that the rear subframe should be immediately replaced as there is a rusted hole in the subframe, "compromising the structural integrity of the rear of the vehicle." We were informed that the prior bulletin issued for 2010-2014 C-Class models did not include our 2015 C-Class. We were quoted over $5200 to repair the subframe. There were no warning messages, lights problems that were noted, prior to inspection. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

My car’s rear subframe was so badly disintegrated due to severe corrosion. It made the driving so dangerous when braking and nearly caused an head-on collision. I have reported this issue under tracking number 11701609 and would like to provide pictures on the corrosion issue.

My wife first noticed loud noise from the back of the car when braking. Subsequently, when I drove it one day after, the car lost balance and nearly went into the opposite direction of the road on a two-lane street. The MB dealership later confirmed the problem was a severely corroded rear subframe that needs to be repaired at very significant expense. This is a serious safety issue that could have caused a head-on collision for me and my wife as a passenger on that occasion. I believe this issue warrants a full investigation by the NHTSA. I understand other Mercedes models such as the 2008-2015 C300 (W204) had the same corrosion issue and was under a recall but my car model (W205) was not covered by this recall. Thank you for your attention to this matter. [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Fuel hose system leaking. Inhalation of gas fumes caused headaches and nausea. Risk of vehicle fire. Yes, the problem has been confirmed by a Mercedes dealer. This is a known issue with Mercedes C300 2015 models and other years. There have been other complaints/lawsuits against Mercedes not wanting to pay for the issue. No warnings just strong gas smell.

Rear subframe completely rusted out. While driving on the hwy I heard a loud noise, a couple minutes later I hit the brakes to slow down to get off my exit and after pressing the brakes the car instantly fishtailed sending me sideways across 2 lanes of traffic. Luckily no one was injured or killed. I’ve seen that the car manufacturer was replacing this issue on models 2008-2015. My vehicle is a 2015 and they are telling me my vehicle is not covered for the issue. The car is not drivable and Mercedes needs to be held accountable. A critical component such as rear subframe completely rusting out in just under 10 years is unheard of and I can’t afford to pay 10k to fix it. Please help

I’m the owner of a Mercedes Benz C- Class Sedan 2015. My Rear Sub Frame Rusted Through at The right trailing arm - Fails state inspection. Mercedes Benz has issued a extended 20 year warranty on all vehicles from 2008 - 2015 C - Class Sedan for Rear Sub Frame that rusted out. Mercedes Benz service advisor stated that my vehicle was not under that extended warranty when he run my vehicle Vin number. My vehicle should be under that warranty, I have the same problem with the same vehicles on the list. Please help. Thank you