Mercedes-Benz GLC 300 stalling problems

Filed Nov 4, 2026 · Transmission · 75,000 miles · CA

The contact owns a 2021 Mercedes-Benz GLC300. The contact stated that while driving 5 MPH, the vehicle stalled and lost motive power, with the check engine warning light illuminated. The vehicle was able to be restarted. The vehicle was taken to a service center, and the contact was provided DTC: P07B7. The contact was informed that the failure was associated with an internal transmission or software programming failure. The contact was informed that the transmission needed to be replaced and was referred to the dealer for additional assistance. The vehicle was scheduled for an appointment with the dealer. The failure mileage was approximately 75,000.

Filed May 7, 2026 · Electrical, Transmission · NY

On April 16, 2026, within minutes of being released from a certified dealership, my 2019 Mercedes-Benz GLC 300 suffered a sudden and total loss of propulsion while traveling at high speed on the Belt Parkway (NY). Despite depressing the accelerator, the vehicle failed to maintain speed and stalled in active traffic. This created an immediate life-safety hazard, forcing me to navigate across multiple lanes without engine power to avoid a high-speed rear-end collision. The vehicle was released to me by Mercedes-Benz of Brooklyn on April 16, 2026, following a repair for which I paid $2,134.94. The dealership diagnosed the issue as a wiring harness/sensor fault and formally certified the vehicle as "Found OK" and safe for operation. The catastrophic failure occurred only 22 minutes after I departed the dealership lot. The vehicle had to be towed back to the facility immediately. Upon the vehicle being towed back on April 16, the dealership admitted via recorded voicemail that the initial $2,134.94 repair was a misdiagnosis. They subsequently issued a new diagnosis for a "Valve Body" failure and a new quote of $6,424. The dealership's Service Director has since admitted the vehicle suffers from concurrent transmission and engine failures, rendering the car a liability. This represents a critical failure of the powertrain and electronic control systems. Releasing a vehicle that suffers a total power loss on a highway immediately after a "certified" repair is gross negligence. I am reporting this to the federal safety agency as a catastrophic failure of a safety-critical component (Transmission/Valve Body) that resulted in a "dead-stick" situation on a major New York thoroughfare, posing a severe risk to myself and other motorists. The vehicle remains at the dealership. Mercedes-Benz USA has offered only a $2,000 "goodwill credit," which does not address the safety defects or the initial misdiagnosis. No recall has been initiated for this batch.

Filed Dec 8, 2025 · Engine · CT

The engine in my 2020 Mercedes-Benz GLC 300 suddenly malfunctioned while driving on two separate occasions. The vehicle began shaking violently and lost power without warning. I could not accelerate and had to pull over immediately. I turned the vehicle off and restarted it to regain limited driveability. On the second incident, the power loss was so abrupt that it felt as if I had been rear-ended. I feared the vehicle would stall in traffic and cause a crash. Following these events, the check engine light remains constantly on. The dealer inspected the vehicle and confirmed excessive valve leakage into the exhaust system, requiring a complete cylinder-head replacement. They warned the failure will worsen and could result in sudden power loss again. This defect poses a serious safety risk. If the power loss occurs while merging or at highway speeds, it could easily lead to a rear-end collision. The vehicle has relatively low mileage for such a severe internal engine failure, and I have learned that other owners of this same engine have reported similar issues. Sudden stalling or loss of acceleration places occupants and other drivers in danger. There were no warning messages prior to the failure, and the problem has recurred. The vehicle is available for inspection, and the defect has been confirmed by a Mercedes-Benz service center. This appears to be a mechanical defect in the engine design, potentially involving valve seat failure. An investigation is needed to determine if this issue is widespread and whether a recall or manufacturer action is required to prevent accidents or injuries.

Filed Dec 3, 2025 · Engine · GA

My 2020 Mercedes-Benz GLC 300 experienced a complete engine failure at ~51,000 miles, shortly after a major repair for a known defect. Initially, the vehicle showed a misfire on cylinder #3, which was diagnosed at RBM of Alpharetta as low compression due to valve seat damage, matching MB TSB LI01.30-P-072328. The cylinder head was replaced in Aug 2025. About two months later, while driving under normal conditions, the vehicle made a loud cranking/knocking noise and completely stalled in traffic without any check engine light or warning. This sudden stall posed a serious safety risk. The vehicle was towed to the same dealer, who has now diagnosed the engine as fully seized and recommended a complete engine replacement. I had also completed the 50,000-mile scheduled service at the same dealer shortly before this failure. Despite this being clearly linked to a known design defect, Mercedes-Benz USA has declined to provide further assistance or goodwill coverage. I am reporting this to highlight both the mechanical failure and the safety risk—this engine seizure occurred without any prior warning lights and could have resulted in a crash. I believe this reflects a systemic failure with the M264 engine in GLC 300s, affecting vehicle reliability and road safety. MBUSA has not provided a written explanation for their denial. I am concerned this issue may affect other GLC 300 owners and deserves investigation or recall consideration.

Filed Nov 21, 2025 · Transmission · 60,000 miles · NY

The contact owns a 2019 Mercedes-Benz GLC300. The contact stated that while shifting from reverse to drive, the vehicle stalled and remained in neutral. After the vehicle stalled, the vehicle took approximately 8 minutes before the vehicle could be shifted into drive. Once in drive, the vehicle would jerk and shift to D3 before accelerating. The check engine warning light would illuminate while in reverse. The vehicle was taken to the dealer, who diagnosed a transmission failure due to a malfunctioning valve body and low pump pressure. The dealer confirmed that the VIN was not under recall and that the issue was not covered under warranty. The vehicle was not repaired. The contact informed the manufacturer of the failure, and a case was opened. The manufacturer referred the contact to the federal safety agency Hotline to report the failure. The failure mileage was approximately 60,000.

Filed Sep 22, 2025 · Engine · VA

Check engine light came on. Code was P219D mixture formation is irregular on cylinder 2. Informed today, the cylinder will need to be replaced entirely for about $10,000. Concerned that although this did not happen to me, others have stated the vehicle completely stalls while driving.

Filed Jul 28, 2025 · Acceleration, Engine · CA

The car does not go into drive from reverse and will sometime automatically shift itself from a low drive gear (D1) into Neutral without warning. After this happens - the car also can't get back into D1. It takes about 20 seconds for the car to shift back into a Drive gear and it will jolt into D3 violently. This has been a scary experience on many occassions - especially at red lights when this happens and we can't get the car out of neutral for some time. This was diagnosed by mercedes dealership near us as a fawlty sensor in the transmission. It is extremely expensive to fix and is specific to mercedes meaning it has to be done by a MB dealership. We applied for good will for assistance but were denied. The car has been maintained very well - this is not a maintenance issue but a specific sensor failure of a mercedes sensor in the transmission. We are thankful no one was hurt - we had our 8 year old daughter in the car when stalling out several times at red lights and it's been a very scary situation.

Filed Jul 2, 2025 · Electrical, Engine · PA

In July 2023, I entered into a lease agreement for a 2023 Mercedes-Benz GLC 300 4MATIC SUV (VIN: [XXX]). From the outset, the vehicle suffered from recurring mechanical failures. It required service visits on August 10, 2023; March 25, 2024; July 26, 2024; September 20, 2024; and October 7, 2024. The final incident on [XXX], involved a fuel pump failure that caused the vehicle to stall in traffic, placing me in a terrifying situation where another driver, enraged and armed, threatened me while I waited for a tow truck. Mercedes-Benz acknowledged the vehicle was inoperable and issued a replacement lease on October 15, 2024 VIN [XXX]. However, this second vehicle also proved defective. Within two weeks, it was back in the shop for service. Since then, it has required repairs on December 24, December 31, 2024, and again on May 28, 2025, including another engine stall that posed a serious road safety threat. Despite my good faith efforts to resolve the matter, Mercedes-Benz, via their claims processor Sedgwick, is attempting to charge me $12,873.52 in negative equity, in addition to fees for Prepaid Maintenance and 4N1 Assurance Protection, as part of their settlement offer. These charges are both inappropriate and unlawful under the principles of lemon law and consumer protection. Request for Relief: •Immediate release from the lease agreement without penalty. •Refund of all payments made toward both defective vehicles. •Full waiver of any negative equity or ancillary product charges. •Any civil penalties deemed appropriate by your office against Mercedes-Benz USA and/or Sedgwick. I have already filed a complaint with the federal safety agency (ID Number: 11665555) As I feel as though my safety is in imminent danger driving this vehicle. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Apr 28, 2025 · Engine · MS

Some M264 Engines are predisposition to premature cylinder head failure, this issue can cause significant misfire issues. It also leads to a costly repair. We experienced issues with a P219D code , we had the coils and plugs replaced on a 2020 GLC 300 with 38.5 k miles. We assumed that this issues with a misfire and check engine light were corrected. My wife was turning onto [XXX] in Pascagoula MS last week, the car misfired and stalled with cars and semi trucks rapidly approaching, several cars had to slam on breaks and this issues almost caused a significant wreck. She had to pull over to gain her composure, the car would not over above 2k RPMs. I showed up and was able to to restart the car , I immediately drove it back to the repair shop. The shop bore scoped the #2 cylinder, the valve seating is significantly damaged, thus causing a significant loss of engine power / misfire in cylinder 2. I reached out to Mercedes Benz USA and was advised to take the GLC300 to the dealer that sold us the car. At present the is being evaluated by the MB dealer. MB USA is well aware of issues regarding cylinder head failure. There is actually a low mileage GLC 300 at MB of Mobile with the same problem as our MB. They have sent out service bulletins to every MB Dealership in the US regarding this issue. Likewise they have extended the warranty on several MB models that share the same engine that are mounted for front wheel drive cars, M260 engine. The M264 is an identical engine that is mounted for rear wheel dive vehicles. It is beyond obvious that a significant loss of engine power poses a threat to the driver/occupants and other vehicles/occupants on the road. MB USA is well aware of this issue with their engines. Not only do they have a service bulletin regarding this matter , they have repair protocols which include a cylinder head replacement. This is a consumer and safety issue that needs to be corrected on applicable GLC 300 models. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMAT

Filed Apr 16, 2025 · Engine · CT

-The malfunctioned component is the Positive Crankcase Ventilation. - Vehicle wanted to stall and did not want to accelerate while in the middle lane on the highway with my family. - Yes it has been diagnosis by certified mechanic - The check engine light turned on at the time of the incident and has been turning on and off ever since.