2021 Mercedes-Benz GLC 300: check engine light

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 20, 2026 · Engine · AL

While driving in my neighborhood at 25 MPH, my Mercedes GLC300 suddenly lost power and the check engine light illuminated. My car would no longer exceed 25-30 MPH, but I drove it straight to the dealership and they said it was a faulty cylinder head and will cost $10,000 to fix! After intense negotiations, they agreed to fix it for $4,205.58, which was better, but still, that’s a lot to pay for a manufacturer’s defect! My car is a 2021 with only 67,540 miles on it.

Filed Feb 17, 2026 · Electrical, Engine · FL

This is a well-known issue with these engines. See TSB (Service Bulletin) The 2021 Mercedes-Benz GLC 300 has 42,000 miles and the warranty ran out 2 weeks ago. The vehicle is up-to-date on service. Fault code P06DA00 Engine Oil Pressure Control Circuit/Open. The Yellow Check Engine Light came on and the engine does not run properly and causes engine damage. We had to drive it slowly, under 45 mph, to the nearest dealership. This is a safety issue. To replace the oil pump control valve solenoid and the wire harness for this feature is $5009.00 at Mercedes-Benz. The part cost is about $300 retail, and the rest is all labor fees.

Filed Jan 8, 2026 · Engine · NJ

Cylinder head valve seat leak ..vehicle Mia fires and check engine light on

Filed Jan 8, 2026 · Engine, Transmission · CA

Vehicle Information: Year: 2021 Make: Mercedes-Benz Model: GLC 300 Engine: M264 Mileage at time of failure: Approximately 65,000 miles Complaint Description: While driving, my 2021 Mercedes-Benz GLC 300 began experiencing repeated engine misfires and rough running, accompanied by a persistent check engine light. These symptoms began shortly after I purchased the vehicle and progressively worsened over time. The vehicle exhibited reduced engine performance and hesitation while driving. The condition was intermittent at first but became more frequent, indicating a progressive mechanical issue rather than a sudden failure. At approximately 65,000 miles, the vehicle was evaluated by an authorized Mercedes-Benz dealership and diagnosed with a catastrophic cylinder head failure, requiring full cylinder head replacement. The estimated repair cost is approximately $8,000. The vehicle has never been modified and has not undergone prior engine repairs. The failure occurred well before what would be considered normal wear for an engine component of this type. Based on the progression of symptoms, the dealer diagnosis, and similar reports from other owners of the same model and engine, this appears to be a systemic defect involving the cylinder head and valve train, rather than an isolated incident or maintenance-related issue. This condition presents a potential safety concern due to loss of engine performance, drivability issues, and the risk of reduced power while operating the vehicle.

Filed Dec 30, 2025 · Engine · NJ

While I was driving on the Garden State Parkway, my vehicle experienced a sudden loss of power and persistent misfires and my check engine light came on. I was put in a position of a significant crash risk due to the fact that the vehicle loss sudden acceleration power while entering the parkway. I was almost rear ended by another vehicle. I drove immediately to a Mercedes-Benz dealer. The dealer confirmed a catastrophic cylinder head engine failure. The vehicle had only 39,000 miles. After some investigating, there have been numerous complaints from vehicle owners with the same issue on the M264 engine (which is what my vehicle has). I request that the federal safety agency investigate the premature cylinder head engine failure. Not only was I put at risk for a possible significant accident, the manufacturer has refused to consider some reimbursement for my $10,000 repair. The vehicle was only 3,000 miles out of warranty at the time of the engine failure. A safety issue seems to be warranted and possibly a recall because of the many complaints on the GLC website. Please investigate.

Filed Oct 28, 2025 · Engine · TX

Twice my car slowed down tremendously in traffic because of a bad cylinder head. I drive a 2021 Mercedes GLC 300 4matic with 33,529 miles. In reviewing other complaints, this is a common and known complaint. My check engine light came on and I could not go over 40 mph. This is very dangerous.

Filed Oct 24, 2025 · Engine · AZ

Car has experienced rough idling, sluggish to no acceleration, check engine light illuminates and no shifting of gears regardless of speed. It appears to be going into limp mode. This has occurred monthly for the last four months. After pulling over, the car is turned off, wait five seconds and then turn it back on the car operates like nothing has happened. Here is when it has happened: 1.In a drive-thru lane to get some food 2.Waiting in a left-hand turn land 3.Driving through a parking lot at 10 mph 4.Driving on a road at 45 mph The date below is the last occurrence.

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 Aug 27, 2025 · Engine · WA

what happened? While driving, all of sudden, engine light was on and shaky with rough vibration consequently loss of power. I pulled over and turned off engine. Engine light disappeared after restarted. It happened again and had diagnostics at the dealership. Software update was given at first solution. However, next day, engine light on again, visited the dealership and it turned out there are leak on cylinder head. It seems a known issue. there are similar cases where vehicle could have been in critical situation. [XXX] [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed May 18, 2025 · Engine · OH

In September 2024 my vehicle's engine light came off and the car was struggling to accelerate, especially in highway. I took it to Mercedes Benz of Cincinnati and they acknowledged the fault, made some repairs (under warranty) but the mechanic told us he had already seen quite a few of these cars needing the engine to be replaced. The problem keep coming back and took in in May 2025 (4 months after warranty expired) with the same exact issue. Now they said it is a cylinder head that needs replacement and that it will cost me $10K. This problem has now been reported by several drivers for this model car within less than 5 years of being made. In Canada, the same type of engine has seen same problem so Mercedes extended the warranty for 15 years on the cylinder heads. They need to do the same for the GLC engines and cover our repairs.

Filed May 14, 2025 · Engine · FL

Our 2021 Mercedes is 4 years old and had the engine light come on. The vehicle has always been maintenance by Mercedes and well taken care of. The engine had a Cylinder Head Failure which resulted in a $7600 repair for a 4 year old vehicle. Mercedes refused to offer a good will repair. This is A major issue reported in 2015–2016 M274 engine which can lead to catastrophic engine failure 1. These failures often result in loss of power, strange engine noises, and in severe cases, engine seizure. The damage can extend to the cylinder head, especially if broken piston fragments impact the combustion chamber. This is a major risk for all owners of 4 cylinder Mercedes. Mercedes of Canada has already issued an extended warranty but owners of US Mercedes vehicles are left on the hook for the bill and risking their lives while this is a known issue.