The vehicle is experiencing an intermittent, sudden, and life-threatening drop into "limp home mode" while driving, creating an severe speed differential with surrounding traffic.First Incident (50,584 miles): The vehicle entered limp mode. Authorized Mercedes service center scanned the car, confirming Fault Code P019185 (Rail pressure sensor malfunction / signal above permissible limit value). The dealer applied an Engine Control Module software patch under Mercedes TSB LI07.70-P-078047.Second Incident (53,695 miles): Less than 3,000 miles later, the exact same sudden powertrain failure recurred. The vehicle drastically lost propulsion power immediately after exiting a high-speed freeway, leaving the driver in an incredibly vulnerable, unsafe position.The manufacturer's documented software remedy has completely failed to fix the underlying powertrain defect, leaving a known hardware component failure unaddressed while actively endangering vehicle occupants.

Source: NHTSA complaint ODI #11760688 · view all complaints for this vehicle at nhtsa.gov

I own a 2021 Mercedes-Benz GLC 300. The vehicle developed moisture/condensation in the headlamp, and the affected headlamp subsequently failed. I took the vehicle to RBM of Alpharetta, an authorized Mercedes-Benz dealership. I was advised that corrosion was found in the affected headlamp and that the headlamp assembly requires replacement. On September 8, 2026, the dealership provided a repair estimate of 3,387.33. The vehicle had approximately 84,769 miles. Mercedes-Benz previously issued NHTSA Recall 22V-261 / Campaign 2022050005 for certain 2021 GLC-Class vehicles because headlamp electrical connections may not have been sufficiently watertight, allowing moisture intrusion that could cause headlamp failure. My vehicle is the same year and model and is experiencing headlamp failure involving moisture and corrosion, but Mercedes-Benz states that my VIN is not included in the recall population. Mercedes-Benz Customer Care opened Case 23963515 and has declined coverage to date. I am concerned that my vehicle may be experiencing the same or a substantially similar moisture-intrusion defect as vehicles covered by Recall 22V-261. A failed headlamp reduces nighttime visibility and presents a safety concern. I am requesting that NHTSA review whether similar headlamp moisture intrusion, corrosion, and failure may be occurring in additional 2021 Mercedes-Benz GLC 300 vehicles outside the original recall population.

Source: NHTSA complaint ODI #11763616 · view all complaints for this vehicle at nhtsa.gov

Vehicle will flash warnings on dash the the blind spot assist in inoperative and the front passenger air bag malfunction. The active brake assist is also malfunctioning as the two white cars colliding is on. The dealership as tried to fix this issue 5 times and has tried argue the the active brake assist is functioning normal.

Source: NHTSA complaint ODI #11499353 · view all complaints for this vehicle at nhtsa.gov

While slowly backing out of the driveway and without contacting anything at all, the rear window completely shattered. The window has never been hit by anything and had no defects yet it completely shattered so clearly reflects a manufacturing defect of some sort that is incredibly dangerous to passengers or other vehicles, since it happens without warning and without the necessity of an impact of any kind.

Source: NHTSA complaint ODI #11641925 · view all complaints for this vehicle at nhtsa.gov