2020 Mercedes-Benz GLC-Class owner complaints

The audible tic-tok sound of the turn signal is way too soft. The sound is supposed to give one notice that the turn signal is on. It simply isn't loud enough to provide that feedback. Consequently I often find that I'm driving down the street having completed a half-turn ( one where it doesn't trigger a shut off) with my turn signal on for blocks before I notice that the turn blinker is still on.

I have had issues with squeaky, very loud noises at slow speed and reverse braking. I have had this issue since I purchased this vehicle. I have brought it in a few times to have 2 different dealers fix the noise as I believe it is a safety issue as well. They said this is a common issue with GLC that they have noises while braking but there is no fix. I had an advisor drive the vehicle and witness loud squeaky noises while braking. Spending a lot of money on this vehicle, and Mercedes should fix this issue. I believe the brake system falls under lemon law and Mercedes should do something to mitigate the issue. The brake pads were okay upon inspection, but pretty soon I will have to pay a lot of money to replace pads at my own expense when the brakes, pads, rotors, etc themselves should be

The front main light on the driver side stopped working after a rain and it continued getting moister in the head lamp every night until a few days ago and as a result the head light assembly does not work at all ,the same thing is happening on the passenger side front head light assembly except it is still working .research showed that this has been a problem on similar Mercedes Benz cars and considering that the car has not had any accidents to possibly causing this it was concluded that this should have been part of the recalls .car is not operatable and i reached out to Mercedes Benz and they acted like I am out of my mind and it is passed the express warranties with car having 69000 miles. I tried explaining to them about the implied warranty and the safety problem and they continue

2020 AMG GLC 43 coupe here in Harrison, NJ. My driving style with this vehicle isn't different in any relevant way versus with past vehicles. There is an acceleration dead spot which is the default occurrence when I am coasting at a low speed and then go to accelerate. Common scenarios are driving toward an intersection and rolling forward as you determine if you are clear to go and then accelerating, or slowing down to let a car in the lane next to you go by so you can then switch lanes and accelerate. I swear, I've almost gotten killed a few times when I had time to go but only if I hustled; depress the accelerator, and nothing happens for a full second. Then I go from having enough time to almost getting hit.

Sunroof stopped working, no longer sits flush with vehicle, will not open. I’ve seen recalls for other models/years regarding unsafe sunroof, potential of detaching sunroof. I believe my vehicle should be included in this recall as well.

My car has Distronic (radar cruise control), and it worked perfectly until I got my car back after routine maintenance (oil change) at my Mercedes Benz dealership in late summer of this year (2023). Now, the system is behaving dangerously aggressive, for example breaking too late for cars in front which have slowed or stopped in stop-and-go freeway traffic. It is acting like the dealership installed a software update for the wrong car (perhaps a lighter weight or lower powered car.) The system has become so disconcerting I've mostly stopped using it because it feels so unsafe.

The rear camera system becomes inoperable when car is first started and put in reverse, then all cameras remain interoperable while driving until sometime later after the car is turned off. This problem occurs intermittently. The symptoms match those described in Mercedes recall campaign 22S20, NHTSA Campaign 22V232. The recall names Mercedes Benz GLC300 but my vehicle’s VIN number does not appear in that campaign. Can it be added?

The contact owns a 2020 Mercedes-Benz GLC300. The contact stated that while stopped at a red light, the vehicle started shaking and jerking. The check engine warning light was illuminated. The vehicle was taken to a dealer where it was diagnosed that the cylinder head needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 40,000.

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 ris

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 dea

Nationwide known cylinder head issues. Cylinder head work needing replaced.

I am the owner of a 2020 Mercedes-Benz GLC300 with the M264 engine. I am hoping that you can assist me with a widely reported, systemic defect: the premature failure of the master cylinder, regardless of vehicle mileage. This issue is extensively documented by numerous owners of the 2020 and 2021 GLC300 models across various public forums, including Reddit and dedicated GLC owner communities. I took my vehicle to Mercedes dealearship for annual service and an intermittent check engine light. The dealership informed me it was a spark plug issue. Once repaired the check engine light went on permanently and the car hesitated as if it would turn off. I brought my car in for service and was told that it was a master cylander failure of the engine. Known Defect: The defect is so widespread tha

The contact owns a 2020 Mercedes-Benz GLC300. The contact stated that while operating the vehicle, the 12-Volt battery warning light remained illuminated. The contact stated that while driving at various speeds, the vehicle shut off. The failure also occurred while driving on a busy freeway. The vehicle was towed to the local dealer who diagnosed that the STOP/START button was faulty and needed to be replaced. The STOP/START button was replaced but the failure persisted. The manufacturer was notified of the failure, but no assistance was provided. The failure mileage was 40,000.

When using engine start/stop function, over the course of 3 days after picking up the car, when at a light, the car did not start back up.

The contact owns a 2020 Mercedes-Benz GLC300. The contact received notification of NHTSA Campaign Number: 21V354000 (Back Over Prevention, Electrical System) however, the part to do the recall repair was unavailable. The contact stated that the manufacturer had exceeded a reasonable amount of time for the recall repair. The manufacturer was made aware of the issue. The contact had not experienced a failure. Parts distribution disconnect.

This vehicle is unsafe. When driving in traffic the engine/transmission will not deliver power in response to throttle application, it is also inconsistent in it's response from one time to the next. The vehicle will hesitate for up to 4-5 seconds before responding to throttle commands when pulling out into traffic. This is most noticeable while rolling between 5-10 MPH and applying power also while making a sharp turn. The powertrain also is extremely inconsistent in it's response which makes pulling into traffic extremely dangerous. I suspect the problem stems from sensors in the electronic stability program (mb esp), the transmission module and the fly by wire throttle and engine control module. Programing of shifts of the transmission seem to fighting within the transmission itself. Al

Winning noise in rear end. We bought used noticed noise getting loader. Took vehicle to dealer. We were informed the rear Differential was bad and would have to be replaced. Vehicle has 61,198 miles on it. Wife drives car around town and on trips out of town. i was told they would have to get replacement form Germany. around $9,088. Dealership has helped with splitting cost $4,544.00. After checking around seems the Mercedes is having some problems with this part. When i escalated to Customer care at MB it took (4) phone calls from me to finally get a response from them. We affeered you half off and nothing there is nothing more we are going to do. But keep receipt incase a recalled happens?? Case # 03071039 (1-800-367-6372). This part should not be something that goes bad on a 2020 with 6

The contact owns a 2020 Mercedes-Benz GLC300. The contact stated that while operating the vehicle, the air bag warning light remained illuminated, indicating that the front passenger’s side seat air bag was inoperable. The cause of the failure was not yet determined. The local dealer and manufacturer were notified of the failure, but no assistance was offered. The failure mileage was approximately 30,000.

Problem (repeat failure / prior warranty replacement): This vehicle has a recurring headlamp defect involving moisture ingress into the headlamp housing/connectors, causing electrical shorting and warning messages, with risk of headlight failure. Mercedes-Benz replaced this same headlamp under warranty in 2021 for the identical issue (moisture/shorting). The defect has recurred on the same vehicle.Recent verification: On Oct 13, 2025, the dealer (Mercedes-Benz of North Palm Beach) observed visible condensation/fogging in the lamp and confirmed it matches the prior failure that was repaired under warranty. Pattern affecting other owners: There are multiple consumer complaints in NHTSA’s database describing condensation, moisture intrusion, shorting, and headlamp malfunctions on GLC vehicle

On Saturday October 5th at roughly 8:30 p.m. heading West on I-94 near battle creek, MI, the glass sunroof on our Mercedes suddenly exploded out and shattered. We were traveling at 75 mph with little surrounding traffic and no over-head obstructions. It took a second to re-gain control of the situation and slow down to a stop. We had the sun-shade closed, saving us from glass shards raining down from the exploded sunroof. The following Monday morning, Oct 7th around 9:00 a.m., we called Mercedes about the issue. They were indifferent and offered no assistance. They pointed out that our MY2020 with 29,711 miles on the odo was not covered under warranty for the sunroof shattering and that we would have to deal with our insurance company. They also informed us that they would not have a