2022 Mercedes-Benz GLC 300 Engine Problems

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

While driving down a busy neighborhood street 2 lanes with cars on both sides making it a 1 lane road pulled over to the side a little to let cars pass. All of a sudden ALL electrical and engine stopped and turned off. Only thing that was powered was instrument cluster with multiple warnings like SRS Malfunction, Steering Malfunction, SOS Inoperative, Parking Brake and more. We believe the car had also shifted to park on its own. No power to anything not even hazard lights. Nothing electrical had any sort of power. Could not even turn car off completely could not get the instrument cluster to turn off with ignition button. When I say everything electrical had no power I mean everything except instrument cluster. Hazard lights power locks, lights of any kind, ignition switch, gear selector, windows, sos feature, nothing had power. I could not imagine having this issue driving on the interstate and having the car completely loose ALL electrical power and what could happen to specially with a SRS malfunction and issue with steering. Had to have a wrecker come with wheel dollys because car could not be put in neutral and towed to Mercedes dealer. Upon their inspection they found the Circuit 30T relay to be stuck in the open position which killed power to everything so the technician replaced the engine compartment pre-fuse panel. It is such a unsafe and very hazardous issue to have a relay failure to where all power is lost especially if you were driving on interstate especially at night with traffic to loose everything electrical even hazard lights and headlights, SRS maltunction, Steering. Mercedes needs to figure this very unsafe issue out.

NHTSA ID

11748161

Incident

Jun 27, 2026

Low coolant warning came on. Battery car didn’t start , had it jump. Low coolant warning came on again. Passenger seat belt warning is on.

NHTSA ID

11736466

Incident

May 4, 2026

See attached document for complaint.

NHTSA ID

11730878

Incident

Mar 11, 2026

The contact owns a 2022 Mercedes-Benz GLC300. The contact stated that while driving at an undisclosed speed, the accelerator pedal was depressed; however, the vehicle failed to accelerate as intended. There was a misfire coming from the engine, and the vehicle lost motive power. In addition, the check engine warning light illuminated. The vehicle was taken to the dealer, where it was diagnosed with spark plug failures, coils, and the transmission needed to be flushed. The vehicle was taken to an alternate dealer where the spark plugs and coils were replaced, and the transmission fluid was flushed. The contact stated that the failure reoccurred. The vehicle was then taken to an independent mechanic who was a Mercedes mechanic, where it was diagnosed with misfire codes in cylinders #1 and #4, leakage coming from exhaust valves in cylinders #1 and #4, low compression in cylinders #1 and #4, and there was a 75 percent leak in cylinders #1 and #4. The contact was informed that the complete head assembly needed to be replaced. The vehicle was not repaired. In addition, the contact stated that the vehicle was repaired under NHTSA Campaign Number: 23V445000 (Fuel System, Gasoline) on 11/2025. The contact stated that the failure began shortly after the recall repair was performed. The manufacturer was not made aware of the failure. The failure mileage was unknown.

NHTSA ID

11705704

Incident

Nov 20, 2025

Multiple loss of power incidents while driving both on surface streets and highways. Causes vehicle to loss acceleration power, vehicle must be pulled over, shut down and restarted to regain power.

NHTSA ID

11694859

Incident

Sep 4, 2025

Defect Summary: Since 2024, my 2022 Mercedes-Benz GLC300 has had a persistent, abnormal engine noise consistent with the sound of a 4-cylinder diesel engine, despite being gasoline-powered. The noise occurs both while idling and in motion. On several occasions, the coolant warning light illuminated while the noise persisted. The defect has worsened over time, becoming louder and more frequent. Events & Safety Risks: The dealership repeatedly claimed “no problem found” because no warning lights appeared and no scanner codes were present, ignoring my time-stamped video evidence. At one point, I was advised to drive the vehicle from Morgan Hill, CA to the dealership while making the loud noise for diagnostics — an unsafe recommendation. When the coolant warning light appeared, the service department planned only to top off coolant. I insisted on a diagnostic, which revealed a coolant hose leak. Driving with a leak could cause overheating and sudden engine failure, creating a serious safety hazard for myself, my child, and other motorists. Repair History: Multiple visits to Mercedes-Benz of San Jose (2024–2025) for the same defect. Each time, the defect was dismissed or not resolved. No meaningful repairs were performed. The issue persists today. Evidence: Time-stamped video proof of defect, full service records, and documentation of correspondence with the dealership are available. Safety Concern: This unresolved defect creates a risk of sudden engine failure or overheating while driving, potentially causing loss of control or stranding occupants in unsafe conditions.

NHTSA ID

11678034

Incident

Oct 11, 2024

My 2022 Mercedes-Benz GLC 300 has been diagnosed with a valve seat failure. This requires a full cylinder head replacement. I purchased this vehicle brand new and have driven it with care, putting approximately 60,000 mostly highway miles on it. Throughout my ownership, I have exclusively used the service at an authorized Mercedes-Benz dealership. Despite my efforts to maintain this vehicle properly, the vehicle began exhibiting misfire issues just outside of the warranty period. The check engine light would flash on and off during a misfire and it presented multiple codes. I returned to a Mercedes-Benz dealership, where I was told the issue is an internal mechanical failure, worn or leaking valve seats requiring full cylinder head replacement with an estimated repair cost of $7,800. Upon researching this issue, I've learned that Technical Service Bulletins exist for this exact failure, and other owners with M264-series engines have experienced identical symptoms and failures. This misfire could happen at anytime, requiring me to stop the vehicle almost immediately. It could cause a dangerous situation in heavy traffic areas with fast moving traffic.

NHTSA ID

11667722

Incident

Dec 1, 2024

While driving on the [XXX] at the speed of 10 to 15miles per hour, I noticed a smoke in the from hood on the passenger side. I felt a danger and stopped the car and got out of the car immediately along with my friend, leaving my belongings phone and other documents etc. Immediately it caught up the fire. I called 911 and reported the incident. Police and Fire engine arrived and tried to stop the fire. I have sent out an email to the dealership as the vehicle is under guaranty and i haven't got any courtesy call to know about the incident. When i tried to call them they didn't even respond to me and hung the phone. I received a call from their sales department and enquiring about if i'm looking for any other vehicle which disappointed me more. I'm in shock and would like this to be investigated as this major security concern. Here is the case# i have logged with manufacturer(Mercedes) Case#:[XXX] CASE#:[XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ID

11650153

Incident

Mar 24, 2025

when ve give gas padle want go above 20 mph and check engin light is on and car shake bad

NHTSA ID

11635429

Incident

Jan 7, 2025

The car randomly shows an empty tank of gas at the start of the day, when there was a half tank of gas remaining. I filled the gas, but the car did not register any fuel-up and kept showing empty. I took it to the dealer for repair and the fuel tank sensor was replaced under warranty a month ago. Now, this week the same issue reappeared. The car began showing no gas in the tank on a random morning last week and remained driveable for a couple of days. The gas levels reappeared corrected on day #3. Today, 4 days later, the car went back to showing zero gas, and shut off while I was driving on an expressway with my minor child in the car. All of the lights on the dash lit up, and the car stopped. It is immovable. It could have caused a severe or fatal accident and this is totally unacceptable!! This is the third time this issue appears on a brand new car that I’ve had less than a year, with 15k miles.

NHTSA ID

11569909

Incident

Feb 5, 2024