2022 Mercedes-Benz GLC 300

See attached document for complaint.

NHTSA ID

11775981

Incident

Jul 3, 2026

My 2022 Mercedes-Benz GLC 300 experienced a significant cooling-system malfunction involving repeated low-coolant warnings, engine overheating, and substantial coolant leakage. Approximately two weeks before the overheating incident, the vehicle began displaying low-coolant warnings. On October 22, 2026, after driving normally and stopping to refuel, I restarted the vehicle. Approximately five minutes later, the dashboard displayed a red warning stating, "Coolant Too Hot. Stop Vehicle. Turn Engine Off." The engine temperature gauge approached the maximum range. I immediately sought a safe location to stop and turned off the engine within approximately one minute of the warning. After allowing the vehicle to cool, I discovered the coolant reservoir was nearly empty. I replenished the coolant, and the warning temporarily disappeared. However, following limited additional driving, the low-coolant warning returned. I subsequently observed substantial coolant leaking beneath the vehicle while it was parked with the engine turned off. The leakage appeared in multiple locations underneath the front and center portions of the vehicle. I documented intermittent dripping followed by sudden streams of fluid, resulting in several visible puddles. This malfunction presents a safety concern because the vehicle experienced rapid overheating during normal operation, requiring an immediate stop to avoid possible engine damage or loss of vehicle operation in traffic. The specific failed component has not yet been identified. The vehicle has not yet undergone a professional diagnostic inspection, but the symptoms and external leakage have been documented through photographs. The vehicle is available for inspection. I am requesting that NHTSA investigate whether this cooling-system failure represents a broader safety concern affecting similarly equipped Mercedes-Benz vehicles.

NHTSA ID

11775013

Incident

Oct 22, 2026

I am reporting a potentially serious vehicle safety issue involving a 2022 Mercedes-Benz GLC after a fatal crash. I was seated in the left rear seat. One occupant died and multiple people were injured. According to the Florida Highway Patrol crash report, the left curtain air bag was listed as “Equipped; Not Deployed,” while the right curtain air bag was listed as “Equipped; Operative; Deployed.” I suffered serious injuries while seated on the same side where the curtain air bag did not deploy. Before the crash, I remember hearing an unusual metallic rattling/clanking noise from the vehicle. I do not know what caused the noise or whether it contributed to the crash, but it occurred before impact. A family member later reported this pre-crash noise to the vehicle’s insurer. Law enforcement indicated that the vehicle’s event data recorder (EDR/“black box”) would be downloaded, but the crash report later stated “EDR Downloaded: No.” To my knowledge, the EDR data was never retrieved or preserved. The insurer later sold the vehicle as salvage before I was able to arrange an independent defect inspection, so the vehicle is no longer available to me for examination. I am not claiming that a defect has been proven. I am asking NHTSA to review whether the documented left-curtain nondeployment, in a crash severe enough to cause a fatality and multiple injuries while the opposite curtain air bag deployed, warrants investigation of the air bag/restraint system or another vehicle component. I am also asking NHTSA to consider the pre-crash metallic noise and the loss of access to the vehicle and EDR data when evaluating this complaint. Because the vehicle and EDR evidence may no longer be recoverable, I respectfully ask NHTSA to evaluate this complaint promptly and compare it with any similar air bag, restraint-system, sensor, or electrical complaints involving this model.

NHTSA ID

11770639

Incident

Aug 15, 2025

The vehicle has experienced two separate incidents of significant loss of power/acceleration. First incident – January 2024, Clarksville, TN: While driving downtown, the vehicle suddenly lost significant power and could not provide normal acceleration. The estimated remaining range was approximately 50 miles. The vehicle was subsequently inspected/serviced by Mercedes-Benz/dealer personnel, but the underlying cause was not conclusively identified or resolved. Second incident- [XXX] [XXX]: While driving in the first lane of [XXX], the vehicle suddenly lost significant power/acceleration when the estimated remaining range was approximately 75 miles. There were no warning alarms or messages before the loss of power. My wife and child were in the vehicle. The vehicle could not provide normal acceleration in highway traffic, creating an extremely dangerous situation. The incident nearly resulted in a serious traffic accident, and my wife had to take immediate action to help avoid a potential collision. The vehicle was subsequently inspected by Mercedes-Benz/dealer personnel, but the specific loss-of-power condition was not conclusively reproduced or confirmed under the circumstances in which it occurred, and the underlying cause was not identified or resolved. The vehicle has therefore experienced this type of serious power-loss condition twice despite service attempts. I can no longer safely drive or intentionally test the vehicle to reproduce this condition. Attempting to drive until approximately 75 miles of remaining range could cause another sudden loss of power and potentially result in a serious accident. I will not intentionally recreate a potentially dangerous failure on a public highway with my family or other motorists at risk. I am reporting this because unexpected loss of power while traveling on a highway presents a serious safety hazard and potential collision risk. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11768413

Incident

May 20, 2026

After recalls performed trouble code P2402 EVAP leak still is present and check engine light is on

NHTSA ID

11760063

Incident

Aug 27, 2026

Rear hatchback for 2026 Mercedes GLC sensors

NHTSA ID

11759362

Incident

Aug 20, 2026

Vehicle: 2022 Mercedes-Benz GLC 300 4MATIC Component: Electronic Parking Brake (EPB) / Service Brakes Summary of Complaint: This vehicle has an ongoing, unresolved Electronic Parking Brake (EPB) defect. The amber EPB warning light has recurred multiple times, including most recently after a $3,000 dealership repair intended to correct this exact fault. Timeline: 1.Following a brake pad replacement, the vehicle experienced an EPB failure, brake fluid loss, and a gear shift interlock lockout — leaving the vehicle inoperable. 2.The vehicle was taken to a Mercedes-Benz dealership for repair. This resulted in a dispute over unauthorized work performed and a request for goodwill coverage tied to a known Mercedes-Benz EPB recall. 3.I paid approximately $3,000 to the dealership for a repair specifically to resolve the EPB fault. 4.Approximately a few weeks after this paid repair, the same amber EPB warning light returned, indicating the underlying defect was not resolved. Safety Concern: The EPB is a safety-critical system. Repeated, unresolved failure of this system — including a prior incident involving brake fluid loss and a gear shift interlock lockout that left the vehicle inoperable — represents a real risk of parking brake failure and loss of vehicle control/immobilization in normal use. Additional Notes: •This defect appears connected to a known Mercedes-Benz EPB recall. •I have photo documentation of the recurring warning light (dated) and the dealership repair invoice for the $3,000 repair. •I have an open case with Mercedes-Benz Customer Assistance regarding this issue.

NHTSA ID

11758847

Incident

Aug 19, 2026

My 2022 Mercedes-Benz GLC 300 (17,700 total miles) suffered a catastrophic structural engine block failure and an explosive loss of propulsion while driving at highway speeds. This occurred exactly 6 days and 183 miles after a franchised Mercedes-Benz dealership performed the official fuel pump impeller safety recall (NHTSA Campaign 23V-445).The dealership's official repair invoice documents that the technician custom-modified the recall remedy by reusing parts, explicitly stating: 'Relocated floater from old pump onto new fuel pump.' Simultaneously with the mechanical engine failure, a 'Reduce Engine Oil Level' message flashed on the dashboard, indicating severe fuel dilution from the compromised fuel system.The dealership is actively violating federal recall mandates by refusing to investigate this failed safety remedy unless I sign an open-ended financial check for a diagnostic and teardown fee. They have also revoked my substitute transportation to coerce payment. Mercedes-Benz USA Corporate Case Number 23652724 has been opened. I am requesting a federal safety investigation into this dealer's non-compliant recall remedy execution."

NHTSA ID

11755637

Incident

Aug 4, 2026

Complaint Customer complaints relating to automatic transmission 725.0 (NAG3 Classic /9G‑TRONIC automatic transmission) and 725.1 (NAG3 facelift/9G‑TRONIC automatic transmission facelift) For faster, more effective and more targeted diagnosis, Intelligent Predictive Repair (IPR) has been developed and integrated into XENTRY Diagnosis. This ensures an automated diagnosis process. Cause As part of the on‑going quality monitoring process and associated quality and damaged part appraisals, a high number of ineffective repairs have been discovered. Such ineffective repairs have a negative impact on all those involved. For the customer, it means high costs and long repair times and for the dealer, it may result in the warranty claim being rejected. Remedy General note: IPR is available for: ‑ NAG3 Classic (automatic transmission 725.0) ‑ NAG3 Classic ‑ AMG sport model (AMG 43 and AMG 53 with converter, automatic transmission 725.0) ‑ NAG3 Classic ‑ Hybrid (automatic transmission 725.0) ‑ NAG3 Classic ‑ AMG 63 (automatic transmission 725.0) ‑ NAG3 MOPF ISG2 (automatic transmission 725.1) ‑ NAG3 MOPF Hybrid (automatic transmission 725.1) ‑ NAG3 MOPF AMG sport model (AMG 53/AMG 53e with ISG48V2 & converter /hybrid, automatic transmission 725.1) ‑ NAG3 MOPF AMG 43/63 with engine 139/177 (automatic transmission 725.1) Steps for the Service Advisor: Important: The more information and detail that can be given to the workshop about the complaint, then the more effective the subsequent diagnosis with IPR can be. To this end, a detailed service reception questionnaire has been provided to help the Service Advisor ask the right questions about the complaint. ‑ Ask precise details about the customer complaint and the conditions and context. ‑ Fill out the service reception questionnaire (please see WIS document: OF27.00‑P‑3000‑05A) for customer complaints in detail and forward it to the workshop. Operation steps for the workshop employee: 1. Perform quick test 2. Access the transmission control unit via XENTRY Diagnosis 3. Select "A customer complaint has been received" and carry out all subsequent operation steps (IPR diagnosis path). 4. The IPR repair instructions are displayed, Carry out the IPR repair instructions without performing any further diagnostic or repair steps. ‑ Important: The IPR repair instructions are binding and must be carried out. Differing repairs are possible; such repairs must be documented in XENTRY in free text. Please observe the information regarding the IPR diagnosis process in XENTRY. Conventional diagnosis and subsequent appropriate repairs are only permitted if IPR does not specify any repair instructions. Invoicing for the guided IPR steps: Operation item 27‑0640 and 0.1 hours Notice regarding warranty: The use of IPR in association with warranty claims is mandatory! If the IPR repair instructions are disregarded without justification, the warranty claims may be rejected and/or are subject to debit. IPR will provide a measure to repair the vehicle based on various data sources (EEPROM, fault codes, etc). Please consider the vehicle maintenance record of the vehicle. For warranty and goodwill repairs, the transmission ECU test log and/or IPR test result must be uploaded into Paperless XENTRY Diagnosis (pXD) . If repair is being determined based of oil pan condition pictures of oil pan MUST be provided to warranty as justification. ·Tamper‑proof documentation: The IPR repair instructions are stored in the control unit log. Please file this document in a tamperproof manner ‑ either in digital form or as a hard‑copy printout and also enclose a printout with the damaged part. In this regard, please comply with the country‑specific warranty requirements of the MPC/general distributor.

Complaint Repeat workshop visit for vehicle vibration while braking from 60MPH. NOTE: Although the symptom is similar to a tire or wheel vibration, it is usually readily noticeable that it is distinctly different if it happens at all times or only while braking. Cause Although the cause of the vibration is most likely due to excessive lateral runout on the rotor or hub/wheel bearing, the system as a whole needs to be checked for other possible contributors. 1. Prior collision damage. 2. Excessive vehicle sitting times without rotating components. 3. Wheel bearing/hub lateral runout. 4. Wheel mating interface has been overtightened (did not follow WIS torque procedures). 5. Mating interfaces have been excessively modified (painted, gouged, bent, etc...). Remedy Read through the entire attached worksheet prior to performing. After performing, please review the final page and perform work accordingly. NOTE: This document is not pre‑authorization or otherwise dealing with warranty. This is intended for diagnostic purposes only. If there are any questions on how to proceed OR The work sheet has been performed and the vehicle has returned with the same concern. Please perform the measurements as seen in the worksheet again and open a TIPS case to the Body, Chassis, and Entertainment team.

Complaint Clanking noise from the area of the speakers in the doors. Cause Under analysis. Remedy To narrow down the cause, first of all remove the door trim. • If the noise continues to occur even with the door trim removed, then continue the diagnosis working towards the speaker and if necessary, create a TIPS case with an informative video as an attachment. Note: Please refer to this document in the warranty claim and, once diagnosis is completed, select the damage code depending on the component part that is causing the issue. • If the noise stops when the door trim is removed, please proceed in accordance with LI72.10‑P‑067691. Information: In this case, do not use a damage code for the speakers in the warranty claim!

Complaint Only vehicles with a variable transfer case are affected. This can be identified through control unit N45 or N15/7 in the quick test. When accelerating with light load, vibrations or jolting sensation may come from the drivetrain. It may be mistaken for a harsh shift. Cause Modified oil quality of the transfer case over time Remedy 1. Check initial quick test for faults in the following control units. N45 or N15/7 ‑ All‑wheel drive (ARS) N127 ‑ 'Drivetrain' (PTCU) control unit Y3/8 ‑ Transmission control for 9‑gear transmission (VGS) N3/10 ‑ Engine electronics for combustion engine If faults are present: Process them as per the guided test in Xentry. If no faults are present: 2. Check the transmission oil level If the oil level is correct: 3. Unplug the connector for the transfer cases control unit and reassess the vehicle on a subsequent test drive If the complaint no longer occurs with the control unit disconnected: 4. Perform an oil change of the transfer case according to WIS specifications ‑ Collect an oil sample of the original fluid 5. Complete all transfer case Tech‑in processes located under VG Control Unit > Adaptations ‑ Resetting the oil service data ‑ Calibration of N15/7 5. Perform road test of vehicle to bring transmission to operating temperature (>60C ) 6. Operate vehicle in full circle with steering at full lock ‑ 5x to the left ‑ 5x to the right Return the vehicle to the client and request they drive the vehicle for at least 200 miles and return if the concern is not resolved. The extended drive will ensure the clutches are properly conditioned with the new oil and should resolve the concern. If this LI has already been applied to the vehicle, please submit a TIPS case to the Powertrain inbox with the following information: ‑ Initial quick test with fault freeze frame data ‑ Initial transmission EEPROM data ‑ VGS and Transfer Case Control Unit Log (N45 or N15/7) ‑ Special Acquisition Data .txt file (Transfer Case Control Unit > Special Procedures > Procedures for support queries to market support > Special Data Acquisition) ‑ Photo of the original oil condition ‑ What color was the fluid drained from the transfer case before the oil change? ‑ Was an oil sample collected, and can you provide a photo of the original fluid? ‑ What color and part number fluid was used during the oil change? ‑ How far was the vehicle driven after?

Complaint Customer complaints relating to automatic transmission 725.0 (NAG3 Classic / 9G‑TRONIC automatic transmission) and 725.1 (NAG3 facelift/9G‑TRONIC automatic transmission facelift) For faster, more effective and more targeted diagnosis, Intelligent Predictive Repair (IPR) has been developed and integrated into XENTRY Diagnosis. This ensures an automated diagnosis process. Cause As part of the on‑going quality monitoring process and associated quality and damaged part appraisals, a high number of ineffective repairs have been discovered. Such ineffective repairs have a negative impact on all those involved. For the customer, it means high costs and long repair times and for the dealer, it may result in the warranty claim being rejected. Remedy General note: IPR is available for: NAG3 Classic (automatic transmission 725.0) NAG3 ‑ AMG sports models (AMG 43 and AMG 53 with converter) NAG3 ‑ AMG 63 NAG3 ‑ Hybrid NAG3 Facelift (automatic transmission 725.1) NAG3 facelift (725.1) with engine 139/177 (AMG 43/63) Steps for the Service Advisor: Important: The more information and detail that can be given to the workshop about the complaint, then the more effective the subsequent diagnosis with IPR can be. To this end, a detailed service reception questionnaire has been provided to help the Service Advisor ask the right questions about the complaint. ·Ask precise details about the customer complaint and the conditions and context. ·Fill out the service reception questionnaire (please see WIS document: OF27. 00‑P‑3000‑05A) for customer complaints in detail and forward it to the workshop. Operation steps for the workshop employee: Perform quick test ·Access the transmission control unit via XENTRY Diagnosis ·Select "A customer complaint has been received" and carry out all subsequent operation steps (IPR diagnosis path). ·The IPR repair instructions are displayed. Carry out the IPR repair instructions without performing any further diagnostic or repair steps. ·Important: The IPR repair instructions are binding and must be carried out. Differing repairs are possible; such repairs must be documented in XENTRY in free text. Please observe the information regarding the IPR diagnosis process in XENTRY. ·Conventional diagnosis and subsequent appropriate repairs are only permitted if IPR does not specify any repair instructions. ·Invoicing for the guided IPR steps: Operation item 27‑0640 and 0.1 hours !!!!! Notice regarding warranty: !!!!! ·The use of IPR in association with warranty claims is mandatory! ·If the IPR repair instructions are disregarded without justification, the warranty claims may be rejected and/or are subject to debit. IPR will provide a measure to repair the vehicle based on various data sources (EEPROM, fault codes, etc). Please consider the vehicle maintenance record of the vehicle. For warranty and goodwill repairs, the transmission ECU test log and/or IPR test result must be uploaded into Paperless XENTRY Diagnosis (pXD) . If repair is being determined based of oil pan condition pictures of oil pan MUST be provided to warranty as justification. ·Tamper‑proof documentation: The IPR repair instructions are stored in the control unit log. Please file this document in a tamperproof manner ‑ either in digital form or as a hard‑copy printout and also enclose a printout with the damaged part. In this regard, please comply with the country‑specific warranty requirements of the MPC/general distributor.

Complaint During part of the steering movement, it feels heavier or more difficult to steer in the same spot every time. OR Rattling, humming, dry sliding/gravel noise from the electric steering system when steering (see attachment). Complaint does not impact the ability to safely steer or control the vehicle. Cause Ball screw drive (KGT) of electric steering damaged by: 1. External force due to: ‑ Hitting the curb/posts with the front wheels. ‑ Driving over obstacles (e.g. pothole/ threshold/ speed bump/ gully) at an inappropriate speed. 2. Corrosion/ water ingress through a damaged boot (see attachment). ‑ Cracks (1) ‑ High pressure cleaner (2) ‑ Animal bite (3) See various examples listed in the attachments for examples of outside influence. Remedy Remove boot clamps closest to steering gear housing on both left and right (as seen in "Steering Rack Boot Clamp Location"). Pull back boot and inspect for rust, broken end stops, water, or any other anomalies. Replace electric steering. Note: Steering gears replaced due to outside influence or damage must not be claimed under warranty!