2021 MERCEDES-BENZ GLB 250 Complaints

Engine showed signs of loss of power and excess noise. It was taken to dealership via MB roadside assistance. At the dealership, they diagnosed it with engine catastrophic failure due to metal parts found in the oil filter. At no time was the engine disassembled to ensure known defects and still under warranty parts were not the cause. Dealer estimated the repair to cost in excess of $22K. MBUSA was contacted and they made no efforts to make the situation whole. The cost estimated was for the complete engine replacement. An engine that only has 53k miles. Although all routine maintenance have been conducted, engine failure was certainly pre-mature. Issues exhibited were excessive engine vibration, loss of power and excess noise.

Escalating Safety Concern – Loud Clunking, Thumping, and Cracking from Front Axle at Low Speeds We are long-time loyal customers and currently own four identical Mercedes-Benz models. Unfortunately, one of our vehicles, a 2021 mb glb250 has recently developed severe clunking, thumping, and loud cracking noises originating from the front axle area, noticeable especially at low speeds. The problem appeared suddenly and is rapidly worsening. After researching the issue, we’ve discovered that many owners of the exact same model and model year report identical symptoms. This appears to be a widespread and recurring problem that raises serious safety concerns, particularly as it affects the front axle and is uncommon in other modern vehicles of this class and young age. Given the potential safety implications and the growing number of affected owners, we respectfully request that Mercedes-Benz investigate this issue promptly, acknowledge it as a known concern, and provide an appropriate inspection and repair at no cost to us. We love the brand and have always trusted its engineering and safety standards, which makes this experience especially distressing. We would greatly appreciate your immediate attention and a clear response on next steps.

While driving, the panoramic moonroof on my 2021 Mercedes-Benz GLB 250 (VIN: [XXX] ) suddenly shattered without any visible impact or prior damage. It sounded like an explosion, and glass rained down into the vehicle. This could have caused serious injury to myself or my child. There was no indication that a rock or debris hit the vehicle. No vehicles were in front of me, and I have no history of impact damage. This seems to have happened spontaneously, and after researching the issue, I found it is a common problem across various Mercedes-Benz models. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

In April 2025, my 2021 Mercedes-Benz GLB 250 (81,000 miles) suffered repeated engine issues caused by a cylinder head failure. The dealer attempted a cylinder head replacement, but during their own test drive after repairs, the engine completely seized and failed again on their property. This indicates a severe defect in the engine assembly that risks sudden power loss while driving, which could cause an accident. Prior to the failure, there were warning messages about misfires and rough idle. The problem has been confirmed by an authorized Mercedes-Benz dealer and the car has been kept at their shop since April, with no resolution. I am concerned this is a recurring safety defect affecting other GLB 250 vehicles. The vehicle is available for inspection and remains undriveable due to the failed engine. I request NHTSA to investigate for possible safety-related design or manufacturing defects that could cause sudden engine seizure and loss of power while driving.

Seat belt failure.Driver side…mechanism… it feels unsafe…the retractor is not locking

Jerking and loud noise from the engine after attempting to accelerate from a red light stop. Vehicle is idling very roughly and almost sounds like a diesel engine. Check engine light came on. Inspection at the dealership found multiple faults for camshaft positions deviating from the specified value. When the oil filter was removed, the shop reported finding some metal particles in the oil. The conclusion was that a mechanical fault caused a metal part in the engine to brake and clog up the engine. The car did not run smoothly after the jerking sound and could have caused an accident if the car was in active motion. The recommendation now is that the engine needs to be replaced.

The contact owns a 2021 Mercedes-Benz GLB250 equipped with Continental Tires, Tire Line: ProContact GX SSR, Tire Line: 235/55/R18, DOT Number: A33LWXX41220. The contact stated while driving 70 MPH, the vehicle began to vibrate with a flapping sound coming from the vehicle. Despite the failure, the contact was able to drive the vehicle to the residence. The contact then drove the vehicle to an independent mechanic where three humps were discovered on the front driver’s side tire that had formed due to thread separation on the inside of the tire. The mechanic referred the contact to a dealer who then referred the contact to the Continental tire manufacturer. The manufacturer informed the contact that the tire should be sent to the headquarters for an inspection. The tire was replaced. The failure mileage was approximately 30,600.

My fuel tank cover would not open. Car was under warranty so MB was able to replace the motor of the fuel cap release. Problem, there is no manual release for the fuel cap so if you are low on fuel and need to fill up, you would be stranded. They need a manual release for the fuel cap for safety.

Entire electrical system went out while driving causing check engine light to come on after the failure of system; there was no dashboard working at all when the system went out; without the dashboard out it was not certain if the vehicle was safe to drive anymore; the dealer has not been able to reproduce the problem; the vehicle has been with the dealer repair system for several weeks and have not been able to determine what happened; they have indicated that the vehicle had some type of water intrusion which short circuited the electrical system; the believes that the water entered into from the windshield area with a possible clogged water drain; there was no prior warning

The contact owns a 2021 Mercedes-Benz GLB250. The contact stated that the vehicle was parked in the garage; however, after driving out of the garage, the contact became aware of a crack on the windshield from the rear-view mirror ten inches downward. The contact stated that the crack seemed to be on the inside over the sensors. The vehicle had not yet been diagnosed or repaired. The dealer nor manufacturer was notified of the failure. The failure mileage was 13,716.