2023 Mercedes-Benz GLC 300 4MATIC

The contact owns a 2023 Mercedes-Benz GLC 300 4MATIC. The contact stated that while driving at an undisclosed speed, the brake pedal was depressed; however, the brake pedal felt as if it had released, and the vehicle failed to stop as needed. The contact stated that the failure was a recurring failure. The dealer was contacted but could not duplicate the failure. The vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 39,000.

NHTSA ID

11752677

Incident

Jul 1, 2026

Mileage

39,000 mi

My 2023 GLC300 suffered a severe, unprovoked emergency brake deployment in traffic, nearly causing a pileup. on [XXX]. The car has only 14,500 miles and has a chronic history of dangerous, unprovoked Active Brake Assist deployments. It broke down twice in its first month of ownership for other reasons, slammed on the brakes during a left-hand turn last year, nearly causing an accident and on [XXX] executed a violent, full-lock emergency stop from 25mph in light traffic with no obstacles in sight, nearly causing a multi-car pileup and putting me thru the windshield. The car was towed to MB of Boston in Somerville under factory warranty on [XXX]. I have refused to drive this hazardous and unsafe vehicle, the Dealer did a quick factory update and an a clean erase of the following code, Code B229BF9, but I have refused to take it back util they have proven to me that this dangerous issue has been fully resolved, I am a [XXX] with a perfect driving record and I frequently drive this car on the highway and I am very fearful the car will do it on the highway which would be catastrophic to me and other motorists. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11747647

Incident

Jun 17, 2026

I purchased a new Mercedes Benz GLC300 2023. Last month, my friend and I were driving on I75 in Florida when we heard what sounded like a loud boom or gunshot. We quickly discovered that my sunroof had exploded. The sunroof was closed, and fortunately so was the sunshade, as large pieces of glass flew off the roof and smaller shards of glass collected on top of the sunshade. My friend and I were fortunate to have not been insured and were able to safely navigate the vehicle to the side of the road to assess the damage. In contacting the MB dealership, I learned that the sunroof is considered "glass" and thus not covered under warranty even though the vehicle is only 3 years old with less than 50,000 miles. What is more concerning to me is that the roof was not under a recall, and there have apparently been other MB owners that have experienced the same issue with class action lawsuits pending. My insurance company covered the repairs following payment for the deductible. This huge safety concern is that we could have been seriously injured by flying and/or falling glass. I write to express my deepest concern over the safety issue the exploding roof presents-the cost of repair relative to what could have happened is minor. Thank you for the attention to this matter.

NHTSA ID

11733932

Incident

Mar 19, 2026

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.

NHTSA ID

11732594

Incident

Mar 31, 2026

The glass panel between the windshield and the sun roof shattered spontaneously

NHTSA ID

11710584

Incident

Jan 5, 2026

When loading groceries in my trunk, the door randomly closes on my head. The last time this door closed while we were loading, I tried stopping it with my hand, by holding it, so my spouse doesnt get smashed, and it will not stop at all. There needs to be a safety feature installed to stop this trunk from closing if a person is underneath it. I fear that a child or an elderly person wont be able to move fast enough and will be severely harmed by this.

NHTSA ID

11699574

Incident

Nov 8, 2025

The contact owns a 2023 Mercedes-Benz GLC300 4Matic. The contact stated that while driving at various speeds and coming to a stop, the vehicle skidded or slid and felt like it had been rear-ended. There was no warning light illuminated. The vehicle was taken to the dealer, but the failure could not be duplicated. The contact stated that the infotainment system was inoperable intermittently. Additionally, the contact stated that while driving 40-50 MPH and depressing the accelerator pedal, the vehicle failed to respond. The contact merged to the right lane to be able to pull over as necessary. There was no warning light illuminated. The vehicle was taken to the dealer to be diagnosed, but the cause of the failure could not be determined. The contact stated that the failure had recurred intermittently. The vehicle was taken back to the dealer. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The failure mileage was unknown.

NHTSA ID

11685231

Incident

Nov 7, 2023

The rear door randomly closes with force unexpectantly. We contacted the Mercedes dealer where the car was purchased and is serviced. They responded it can not be fixed and was an ongoing concern of many owners

NHTSA ID

11664589

Incident

Jun 3, 2025

Complaint Diverse functional limitations in the vehicle in combination with various warning and fault messages in the instrument cluster display. Cause Communication timeouts mean that communication errors may occur in the on‑board electrical system, which can result in various fault messages being displayed in the instrument cluster. This could be down to delayed feedback from the drivetrain control unit (N127) (CPC) to other control units networked to the CAN bus. Information: Only valid for vehicles through production period 10/2025. Not valid for vehicles with control unit CDCC (N125, central controller charging and driving) • It may not be possible to attribute any communication errors stored in the control units on the CAN bus to a specific cause • In rare instances, there may be a brief activation of the yellow warning lamp for engine diagnosis or there may be a sporadic delay with the start enable. • There may not be any specific fault codes present that indicate a specific component. Example image: Fault messages in instrument cluster: The reason for this could be down to delayed feedback from the control unit CPC3 to other control units networked on the CAN bus. Remedy Do not replace any components!!! ******************************************************************************************************* 1. Connect charger (see AR54.10‑P‑1127WT). Note: An adequate voltage from the on‑board electrical system battery must be guaranteed for the entire duration of the work procedure. Otherwise, the control units could be damaged if an undervoltage occurs. Information: Observe the operating instructions of the charger. Information: Use the charger to ensure an adequate voltage (at least 12.5 V) from the on‑board electrical system battery. ‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑ 2. Connect diagnostic system (see AD00.00‑P‑2000‑06FR). Note: Always use the latest XENTRY Diagnostics software release. Information: Strict compliance with the operation steps in XENTRY Diagnostics is absolutely essential. ‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑ 3. Select control unit N127 (CPC) via the direct link using XENTRY Diagnosis. Information: To do so, select the following menu items: Control units view → Drive systems → N127 ‑ "Drivetrain" control unit (CPC) ‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑ 4. Update software for control unit N127 (CPC) (see AR54.21‑P‑0014‑01Y). Info: To do so, select the following menu items: Adaptations → Control unit update → Update control unit software. Information: You are then automatically guided through the steps "Update of control unit software" and "SCN coding". Always observe the following operation steps at all times ‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑ 5. Disconnect diagnostic device from vehicle (see AD00.00‑P‑2000‑06FR). ‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑ 6. Disconnect charger from vehicle (see AR54.10‑P‑1127WT).

Complaint Wheezing noises/squeaking noises from the front shock absorbers when passing over surface undulations and rough road. Noise MUST match those heard in the attached videos. Cause • Wheezing noises: Flow noises of the damper oil • Squeaking noises: From the mechanical rubber valve in the dividing piston Remedy In case of complaints, the front shock absorbers must be replaced. If shocks have been replaced and noise persists, please open a TIPS case to the Body, Chassis, Entertainment inbox.

Complaint Wheezing noises/squeaking noises from the front shock absorbers when passing over surface undulations and rough road. Noise MUST match those heard in the attached videos. Cause • Wheezing noises: Flow noises of the damper oil • Squeaking noises: From the mechanical rubber valve in the dividing piston Remedy In case of complaints, the front shock absorbers must be replaced. If shocks have been replaced and noise persists, please open a TIPS case to the Body, Chassis, Entertainment inbox.

Complaint Oil seeping from turbocharger oil return line at connection to engine block. Low oil level warning. Oil observed under vehicle. Cause Return line under tension due to turbo rotation. Remedy Inspect turbocharger housing for rotation (refer to attachment). If rotation is confirmed, the turbocharger and oil return line must be replaced.‑Resealing or replacing only the oil return line is not sufficient and will not resolve the symptom.‑Clean noise insulation on right side of engine if necessary. Replace insulation if cleaning is not sufficient.‑Observe foot notes regarding additional parts in XENTRY parts information when ordering turbocharger.

Issue A software update will be performed that provides enhancements to the robustness and system stability of the communication module. The update is free of charge and runs in the background, which takes about 8 minutes to install. During this time, the vehicle can be driven without any restrictions, and the new software will be active with the next ignition cycle. Remedy MBUSA will conduct an OTA service campaign. Remote software updates are automatically downloaded and installed in the customer’s vehicle free of charge and do not require a dealer visit.

Complaint Slight creaking noises when steering. Cause Noises may come from one or more sleeves of the horn contact plate. Remedy Remove the horn contact plate and check the sleeves for noise; see attached video. If necessary, apply lubricant to the sleeves.