Mercedes-Benz GLC-Class Complaints

782 consumer complaints on file.

#11732486April 20, 2026
UNKNOWN OR OTHER
My sunroof exploded while driving on the interstate.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11732594April 20, 2026
FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL, VEHICLE SPEED CONTROL, UNKNOWN OR OTHER
The issue is regarding the “Traffic Sign Assist” (Owner’s Manual page 221) feature of the Adaptive Cruise Control System. Vehicle will be made available if requested. The function of the "Traffic Sign Assist" is to monitor roadside "Speed Limit" signs and the cruise control will increase or decrease speed to stay within the permissible legal speed limit. The system worked except occasionally it would change the indicated permissible speed limit on the instrument display when there is no corresponding roadside speed limit sign and the permissible speed limit for that stretch of roadway is unchanged. When this happens, suddenly and abruptly, the vehicle display would indicate a "phantom" Higher or Lower Speed Limit sign and rapidly and abruptly accelerate or decelerate. Again there were no roadside signs posted indicating a higher or lower speed limit! The risk is potential for rear end collisions from or to other traffic due to the abrupt acceleration or deceleration. when we returned home from a 4556 mile road trip, we took the vehicle to the Mercedes dealer for routine service and mentioned this to the Service Advisor. He indicated that when this defect is reported their solution is to deactivate the system. I don't feel this is adequate since another driver could reactivate the system through the settings. It has not been inspected by anyone except the dealer. There were no warning lamps, messages or other symptoms before the display changed and the vehicle abruptly accelerated or decelerated.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11731548April 16, 2026
FUEL/PROPULSION SYSTEM
I was driving back to my house in york, PA. My car all the sudden changed the gear from “D” to “N”. My gas meter was showing 106 miles. my didn’t give sign or alert before it shifted the gear from D to N. I was driving on highway and this was major safety concern as I could have hit by cars coming on highway speed. We had this similar incident last year as well but we were at traffic light stopped so we didn’t realize that time that car shift the grear by itself. Once we fill the gas, we were able to drive back home but it was scary and big safety concern that car doesn’t give any notification or alert for low fuel and change gear all the sudden.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11730878April 13, 2026
ENGINE AND ENGINE COOLING
See attached document for complaint.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11730496April 10, 2026
SERVICE BRAKES
3/31/26 2pm After highway driving - 3 miles/35 mph tried to brake- Immediately something was wrong with the brake as and it felt spongy/mushy/unresponsive. Car did not slow until I pressed the brake fully to the floor. The car did stop &was alarmingly unresponsive. Around this time,noticed the white BRAKE light illuminated. Continued to drive - terrified. Had to brake VERY HARD to get car to slow/stop. at home, Quick google search had me try turning on and off parking brake - tied this 5-6 times and white BRAKE light went off and I could brake/stop car. Bought car to Mercedes for service for 4:20 appointment - expressing incredibly strong reservations to Will Bane -and fear about driving car. He assured me as it is braking it should be fine. 04/01/2026 -notified car was ready for pick up/text stated: "Service is complete, everything looked good on the inspection report. No codes in the system for the brake concern and the brakes are currently working as designed" at pickup - and prior in text to will bane - i expressed significant concern about future braking issues. was told it was a "software issue and they updated it" and given a card for roadside assistance There was a recall campaign (2026010002/25p5496612) and codes were cleared as part of this unrelated recall. Brake fluid exchange was performed PRIOR to brake diagnosis Bottom line - I have significant concerns about braking.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11729806April 7, 2026
ELECTRICAL SYSTEM
All of the screens in the car failed to start. They remained black while the car was running. Turning the car off did nothing. Drove to a parking lot, turned the car off, got out, locked the car, waited 5 minutes and it still didn't come back. Had to do a reboot by holding the system power button for 10 seconds. This has occurred 3x in 9,200 miles.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11729435April 6, 2026
VISIBILITY:SUN/MOON ROOF ASSEMBLY
The contact owns a 2019 Mercedes-Benz GLC300. The contact stated that while driving 65 MPH on the interstate, the sunroof suddenly shattered into pieces and flew off the vehicle. The vehicle was driven to a dealer but was not repaired. The manufacturer was notified of the failure. The failure mileage was 106,706.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11728476April 1, 2026
UNKNOWN OR OTHER
I have a MC Benz 300 GLC with $50,000 miles. I was having heating issues so took it to the dealership, which basically advised of the issue describer below, which would cost $14k to repair. Contaminated coolant in Mercedes-Benz GLC 300 models often results from the internal failure of a "desiccant bag" inside the coolant expansion tank, which disintegrates, releasing material that clogs the heater core. Symptoms include black residue in the tank, reduced cabin heat, and engine overheating. Key actions include replacing the expansion tank (reservoir) and flushing the entire system.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11726943March 25, 2026
AIR BAGS, SEAT BELTS
A message that passenger air bag is damaged/will not deploy appears. Passenger seat belt gets stuck and cannot be opened. Check engine light on-pvc valve issue most likely.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11726336March 23, 2026
ELECTRICAL SYSTEM
The contact leased a 2025 Mercedes-Benz GLC300. The contact stated that while driving at 45 MPH, the instrument panel and the infotainment system screen turned black, and the vehicle made abnormal electrical snapping sounds. The vehicle was taken to the dealer, where two software resets were performed days apart; however, the failure persisted. The dealer informed the contact that upon performing a third software reset and replacing the circuit breaker fuse, the vehicle would be repaired. The dealer and the manufacturer were contacted and informed the contact that it was a common failure. The failure mileage was approximately 4,700.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11725658March 19, 2026
ELECTRICAL SYSTEM
The contact owns a 2023 Mercedes-Benz GLC300. The contact stated that while driving at an undisclosed speed, the speed limit warning system failed to function as intended. The contact stated that while driving 60 MPH, the Heads-up Display (HUD) illuminated a red light and an unknown message about driving too slowly was displayed. The contact stated that the red light illuminated and flashed intermittently. The vehicle was taken to the dealer, and the contact was informed that the failure was common with the vehicle. The vehicle was not repaired. The contact stated that the failure persisted. The contact asked if the speed limit warning system could be deactivated, and the dealer was informed that it had to be approved by the manufacturer. The manufacturer was made aware of the failure. The contact was referred to the dealer for assistance. The contact stated that the dealer and the manufacturer offered no assistance. The failure mileage was approximately 12,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11725180March 18, 2026
SUSPENSION, POWER TRAIN, ENGINE
This 2021 Mercedes-Benz GLC 63 AMG has experienced repeated and escalating warranty defects involving engine performance, loss of acceleration, air suspension failure, and now inoperative advanced safety systems including blind spot and active brake assist. Despite numerous repair attempts at authorized dealerships, including extensive engine teardown and cylinder head replacement, the manufacturer has been unable to permanently repair the vehicle. The car has been out of service for 145 cumulative days to date and continues to exhibit safety-related failures. It is currently back at the dealership for service. The vehicle therefore qualifies as a lemon and the owner seeks statutory relief in the form of a buyback and compensation. Please see the attached invoices for additional details and timeline below. Service Repair Timeline 2023 ● Air suspension diagnostics & component replacement Dec 5, 2023 (1 day) Invoice #160689 2024 ● Loss of acceleration ● Vehicle enters limp mode ● Fuel pressure sensor replaced ● Multi-day service hold ● Recurrent suspension malfunction ● "Do not drive over 50 mph" warnings ● Valve block / fuse / compressor diagnostics ● Check Engine Light ● Rough running ● Misfire cylinder 2 ● Ignition coils, plugs, injector replaced ● Vehicle held for extended diagnostics ● Compression loss discovered ● Valve seat damage ● Cylinder head removal & replacement ● Extensive engine teardown ● Vehicle out of service 103 consecutive days March 22, 2024-March 29, 2024 (8 days) Invoice #162719 March 29, 2024-April 11, 2024 (14 days) Invoice #162840 April 28, 2024-May 1, 2024 (4 days) Invoice #163306 May 2, 2024-August 12, 2024 (103 days) Invoice #289050 August 21, 2024-August 30, 2024 (8 days) Invoice #292684 August 28, 2024 (1 day) Invoice #292920 October 8, 2024 (1 day) 2026 ● Recurrent warnings ● Check Engine Light ● Blind Spot Assist inoperative ● Active Brake Assist limited ● Recurrent suspension malfunction (3rd time) ● "Do not drive over 50 mph" warning
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11725254March 18, 2026
FORWARD COLLISION AVOIDANCE: AUTOMATIC EMERGENCY BRAKING, ELECTRICAL SYSTEM
There are two issues 1) Unsure of the exact date, but about a year or two ago we were driving our car and the car's automatic break system went into effect on a typically busy, 3 lane road despite there not being any cars in front of our vehicle. We took it into the dealership, who confirmed the issue and told us that sometimes the automatic brake mis-identifies the metal plates in the roads to be vehicles. Had there been a car driving behind us at the time this was happening, it could have been a major accident as the speed limit on that road was 45mph. Additionally we had our [XXX] in the car. There were no warning lamps, messages or symptoms of the problem prior to failure. 2) Recently we have been having a warning sign on our car that says the 12v battery is low, even though it should not be. Historically this would tell us to drive our car around so the battery wouldn't die, but this would sometimes turn on even after a 30+ minute drive. It was turning on every single time we turned the car off, so we brought it into the shop. While in the shop, the dealer provided us with a brand new GLC 300. I took this GLC 300 to my son's daycare to drop him off and when I returned to the car I received an error message "48V battery service required" and could not turn on the vehicle. This brand new vehicle left me stranded. While I was safe at my son's daycare, this has caused me to have significant concerns around the safety and reliability of these GLC300s. We are planning on taking our 2023 GLC 300 on a 6 hour road trip with our [XXX] old and [XXX] old and I am very concerned about the car not starting if we stop for gas. What if we get stranded in a small city along the way? INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11724468March 15, 2026
POWER TRAIN
The engine starts shaking, smell of gas car than stops while driving, could caused an accident and severely injured someone on the freeway. This is a major safety issue after further researching this particular issue MB of Canada issue a warranty letter extension for this particular but nothing for US.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11724095March 13, 2026
EXTERIOR LIGHTING
Headlight is defective and is filled with condensation which has caused the entire light to fail. The problem has been confirmed by a independent service center. The light has not been inspected by a manufacturer however the manufacturer was contacted and denied that a recall exists however other purchasers have reported the same issue. There have been no apparent issues prior to this problem.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11724158March 13, 2026
BACK OVER PREVENTION: SENSING SYSTEM: CAMERA
The contact owns a 2021 Mercedes-Benz GLC300. The contact stated that the rear-view camera was not functioning properly. After restarting the vehicle, the camera operated as needed; however, several days later, the camera became inoperable. The contact referenced NHTSA Campaign Number: 21V354000 (Back Over Prevention, Electrical System); however, the VIN was not included in the recall. The dealer was not notified of the failure. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 96,000.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11723770March 12, 2026
STRUCTURE:BODY:HATCHBACK/LIFTGATE, FORWARD COLLISION AVOIDANCE: AUTOMATIC EMERGENCY BRAKING, ELECTRICAL SYSTEM
See attached document for complaint.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11723692March 11, 2026
FORWARD COLLISION AVOIDANCE: AUTOMATIC EMERGENCY BRAKING, FORWARD COLLISION AVOIDANCE: WARNINGS, LANE DEPARTURE: BLIND SPOT DETECTION
To the Office of Defects Investigation National Highway Traffic Safety Administration I am submitting this complaint to formally report a serious and recurring safety defect involving the automatic braking and collision detection systems in our Mercedes-Benz GLC. License Plate: 9RHN710 Dealer Servicing Vehicle: Mercedes-Benz of Stevens Creek (AutoNation), San Jose, California The vehicle has repeatedly experienced unexpected and unprovoked braking events, including situations where the automatic braking system engages despite there being no vehicles, pedestrians, or visible obstructions present. The issues observed include: • Sudden automatic braking activation without obstruction • Unexpected vehicle deceleration during normal driving conditions • Repeated dashboard alerts indicating “Speed Severely Restricted” • Repeated Attention Assist / “Coffee Break” warnings during normal local driving • Sudden brake engagement when parking, accompanied by a loud mechanical noise These events create a dangerous driving condition, as unexpected braking could lead to a rear-end collision from vehicles traveling behind the driver. During one incident, the abrupt braking caused a severe jolt to the driver, resulting in whiplash symptoms that required medical evaluation and MRI imaging, which identified cervical strain. The vehicle has been brought to the authorized dealership multiple times for inspection and repair attempts. However: • The dealership has not been able to diagnose or repair the issue • Service visits have largely been documented as general inspections • No ADAS (Advanced Driver Assistance Systems) diagnostic or calibration report has been provided, despite the fact that the malfunction appears directly related to radar, camera, or collision prevention systems. We respectfully request that the Office of Defects Investigation review this complaint and determine whether further investigation into this issue is warranted.
Crash:
No
Fire:
No
Injuries:
1
Deaths:
0
#11723228March 10, 2026
STRUCTURE:BODY
While driving on interstate 4 in Florida with our grandchildren going approximately 70 mph the sunroof on our 2018 Mercedes GLC just exploded no object came into the vehicle and while glass came into the vehiclenot all the glass that made up the sunroof came into vehicle suggesting a pressure issue as apparently blew out
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0
#11722368March 5, 2026
ELECTRICAL SYSTEM
I purchased a brand new GLC 300 on May 25, 2023. By June 2, 2023 I was already stranded due to a 12V battery electrical system failure. Since then I have been stranded 8 total times and the vehicle has been in the service department 14+ times for repeated electrical issues (8 of those visits were related to the same 12V battery electrical system failures. The battery was reportedly replaced in 2024-shortly thereafter I began experiencing issues with the collision assist malfunctioning. The alarms would sound seat belt tighten and brakes lock up while driving on the interstate. The theft deterrent alarm wound sound in the middle of the night without provocation. The panoramic roof would malfunction. The air vent disintegrated. In August 2025, the collision assist malfunctioned causing the vehicle to steer off the road resulting in a blow out. It has not been driven since.
Crash:
No
Fire:
No
Injuries:
0
Deaths:
0

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