Sedan, gasoline, AWD/All-Wheel Drive, built in United States. Owner complaints on file from Jan 8, 2018 to Sep 2, 2026.
Owner complaints about this model year, by the year they were filed with NHTSA.
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The full text of every complaint filed with NHTSA about this model year, newest first. Complaints are filed by owners and are not verified by NHTSA; NHTSA removes personal details before publishing.
29 complaints on file, page 1 of 2.
I am reporting a potential safety defect involving the locking/key-detection system in my 2015 Mercedes-Benz C300. On [XXX], at approximately [XXX] p.m. in Coral Ridge, Fort Lauderdale, I secured my young son in his car seat. My purse, containing the key fob, and my phone were on the front passenger seat. I closed the door and walked around to the driver's side. The vehicle had locked all doors by itself. I did not press the lock button or intentionally lock the vehicle. There were no warning lights, messages, alerts, or other symptoms beforehand. My [XXX] son was trapped inside the locked vehicle, and both my key and phone were also inside, leaving me unable to access him or call for help. I flagged down a passing car, and we ultimately had to break a window to reach him. The vehicle has not been inspected by Mercedes-Benz, a dealer, police, insurance, or an independent service center, and the issue has not been reproduced or confirmed. After replacing the window, I have not attempted to recreate the incident because of the safety risk. The vehicle remains available for inspection upon request. I am concerned that the vehicle can lock with the key fob inside the passenger side, creating a potentially serious risk if a child or vulnerable occupant is trapped inside, particularly in hot weather or where immediate assistance is unavailable. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
NHTSA complaint 11761726I am a mechanic speaking on the behalf of a customer; this customer is experiencing problems with her rear subframe. The older generation of her car has a famous issue with rear subframe rusting out. Her car uses an updated part number that is almost identical in construction to the failure prone part that was famous for rusting out, although they are NOT the same number. The failure prone number is 2123503805 or 2043500141, they are installed on the older chassis, w204, w212, etc. The part that is in THIS vehicle is 2123503605, the construction is almost identical to the part numbers listed for the w212 and w204 provided above. There is no drainage holes provided for water that has entered through rain or any other detritus that will permeate on the road's surfaces through natural progression of the vehicle's life, like on the older chassis. The material used is steel with paint on the outside instead of some sort of encapsulation that coats both inside and outside surfaces. And because these don't have any sort of ability to evacuate any substances, they are interacting with unprotected metal and will react into rust. This failure can lead to misalignment at the very minimum of problems, at the worst, it can cause control arms falling off, causing wheel hub assemblies to fall off, this shouldn't have to be explained but this can cause major injury or death, not only to the passengers to the vehicle, but to others who share the misfortune of being at the wrong place at the wrong time. And, the understanding of these not being the SAME part shouldn't warrant the extension of the recall to these particular vehicles, but the failures are similar to what was seen before on other older vehicles and should warrant further investigation. With hope, this could just be an isolated incident, but since patterns are uncanny, this should be investigated with some interest to the public wellbeing. Cordially Naseam F. Samaan Licensed Virginia State Inspector. Sanko Auto Care
NHTSA complaint 11760266Vehicle rear subframe has rusted through, causing vehicle to swerve upon braking, making the car unsafe to drive for the occupant, other vehicles on the road, and pedestrians. Mercedes dealer has advised that subframe has rusted through, requires replacement. The car will be brought to the dealer for repair (at owner's expense) by Friday, 8/28/2026. We can request that the dealer provide us with the subframe - please advise. The vehicle provided no warning indications.
NHTSA complaint 11759222An inspection of my vehicle on August 6, 2026 disclosed that the rear subframe has corrosion, including perforation. It is my understanding that this problem has been identified in mine and many other Mercedes-Benz models, and that Mercedes-Benz has offered an extended warranty to replace the subframe in certain of these models, but my model for the year it was manufactured was not included. I was not made aware of this potential problem by Mercedes-Benz, and they are not offering an extended warranty to resolve this serious safety issue.
NHTSA complaint 11757917During a mandatory Virginia State Safety Inspection, the vehicle failed due to severe structural corrosion and perforation of the rear subframe. Because these components notoriously corrode from the inside out, the fact that the rust is externally visible and structurally failing indicates an advanced, catastrophic material breakdown.The rear subframe serves as the foundational load-bearing anchor for the rear suspension and control arms. This level of structural rot poses an immediate, severe safety hazard. Had the failure occurred while driving at highway speeds rather than being caught during an inspection, the suspension mounts could have catastrophically detached, causing a sudden loss of vehicle control, unpredictable fishtailing, and an imminent crash risk. There are absolutely no dashboard warning lights, diagnostic trouble codes (DTCs), or driving indicators to alert the driver of this structural degradation. The defect remains entirely hidden until the metal physically fractures or the vehicle fails a professional inspection. Furthermore, because neighboring states (such as Maryland) do not mandate annual safety inspections, this severe structural failure will go entirely unnoticed by thousands of drivers until a catastrophic on-road failure occurs. Mercedes-Benz has already explicitly acknowledged this exact engineering and material defect in the preceding W204 generation (C-Class models up to 2015), subsequently issuing a 20-year, unlimited-mileage extended warranty for rear subframe corrosion. However, Mercedes-Benz has arbitrarily excluded my 2015 W205 C-Class model from this coverage, despite the vehicle employing a highly similar subframe design that suffers from the exact same moisture-trapping and premature rotting failure mechanism. This represents an unaddressed, systemic manufacturing defect that poses an immediate risk to public safety. I’ve included two photos showing holes in the subframe from rusting inside out.
NHTSA complaint 11754785Car was pulling to one side. Replaced the front routers and breaks. Problem still persisted. After more investigating the subframe was found to be rusting out, Mercedes of New London CT said it was unsafe to drive. But allowed my daughter to drive it home. This car was purchased it brand new from Mercedes=Benz of Warwick. The car was garaged all it life. This should not happen. They have had recalls and problems with this model just not this one. My concern is the safety of those driving this model clearly the problem was not solved. Please make Mercedes notify people driving this model, that there is a known subframe corrosion issue.
NHTSA complaint 11750145My 2015 C300 W205 failed at its state inspection today due to a rusted through rear subframe. I understand that the W204 warranty on this was extended to 20 years/unlimited miles but the W205 was not. I have contacted Mercedes customer care for a potential goodwill repair since this seems to be a known issue with class actions pending. This should not be failing and it’s unclear why Mercedes did not include all models with the same design in its extended warranty. The costs could be up to $7k.
NHTSA complaint 11741830The car would seem to shift when stopping , when tires were removed the rear subframe had rusted out completely, this is a major safety issue and could cause loss of control of the vehicle. The failure is the same as what the w204s experienced but they’re being fixed at the cost of Mercedes
NHTSA complaint 11738382Component/System Failure: The rear subframe on my 2015 Mercedes-Benz C300 failed due to severe corrosion/rusting. The subframe is available for inspection upon request. Safety Risk: This failure created a serious and immediate safety hazard. While driving at highway speeds, the structural integrity of the vehicle was compromised, I had to break and lost control of the vehicle and almost causing a crash. This also posed a danger to other drivers on the road. The condition was severe enough that I believe I narrowly avoided a major accident. Confirmation of Problem: The issue has been confirmed by a Mercedes-Benz dealership service department, who identified the subframe as rusted and structurally compromised. Inspection by Other Parties: The vehicle has been inspected by a Mercedes-Benz dealership. It has not yet been inspected by the manufacturer directly, police, or insurance representatives. Warning Signs Prior to Failure: There were no clear warning lights or dashboard messages indicating this issue prior to the failure. The problem appears to have progressed without visible warning until it became severe. Additional Context / History: Mercedes-Benz has acknowledged subframe corrosion defects in certain vehicles from approximately 2010–2020, but my specific vehicle was not included in the extended warranty coverage. This is the second Mercedes-Benz vehicle I have owned (previously a 2012 model) that has experienced the same subframe failure. I was previously told that this issue had been resolved in newer models, which influenced my decision to purchase this vehicle. Additionally, this vehicle was purchased as a Certified Pre-Owned Mercedes-Benz, which implies it passed a detailed inspection process. Despite this, a major structural component failed. A warranty claim was submitted but denied on the basis of “rust,” even though this appears consistent with a known factory defect.
NHTSA complaint 11734527rusted rear subframe. unsafe braking and suspension due to this. damage code 35441 47 shows 2008-2015 vins but my vin does not show active recall, yet has the issue
NHTSA complaint 11734426The rear of the car would begin to slip during turns and when brakes were applied. When I had the issue checked out, my mechanic said that the rear subframe has severe corrosion, rust and holes. The subframe perforation is causing instability in the rear wheels, which is a safety issue. I took the car to Mercedes for an inspection and they confirmed the holes in the sub frame,with the inspector stating that the sub frame is "about to fall off". I believe this to be a safety issue as having the wheels or subframe fall off could cause fatalities. This appears to be a manufacturing defect given recalls for the same issue in other models of the 2015 c300. See video of the inspection of my car here: [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
NHTSA complaint 11734329Mercedes issued a recall for Mercedes C class for the model year up to 2015 for rear subframe that is rusting with holes in it. The dealer tells me my car is not covered by Mercedes even though it is a 2015 model. They gave me an estimate for the repair of over $5000. They say the model changed mid 2015 and mine is a model that is not covered. This could cause a serious crash at high speed. I am not sure why that repair is not covered for my 2015 model & I would like Mercedes to honor the repair.
NHTSA complaint 11733647The 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.
NHTSA complaint 11729890Exhaust camshaft pulse wheel shifted on camshaft. Replacement of camshaft, positioner, oil control valve, timing chain and chain tension was recommended.
NHTSA complaint 11729855When 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.
NHTSA complaint 11726706Rear subframe rotted, hole like perforation on the frame. The current extended warranty covers the C204, but my Mercedes C300 2015 has a C205 that is the same part number, but for some reason the warranty does not cover the C205, but has the same identical issues as the C204.
NHTSA complaint 11726150The 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
NHTSA complaint 11724992REAR SUBFRAME RUSTED OUT AND BROKEN
NHTSA complaint 11724694Fuel 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.
NHTSA complaint 11721304After 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 .
NHTSA complaint 11720037Technical service bulletins and other notices the manufacturer sent to dealers. A bulletin is not a recall; the 60 most recent are listed.