2015 MERCEDES-BENZ C200

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)

I 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

Vehicle 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.

An 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.

During 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.

Car 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.

My 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.

Component/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.