2023 Mercedes-Benz GLC 300 Problems

What owners report

Owners of this model year most often describe 12V and 48V electrical warnings, including sudden no-start episodes and shutdowns while driving, and several of these describe problems in the first weeks of ownership. Check engine light complaints are also common, often with the light coming and going and no fault found at the dealer. Smaller groups describe unexpected automatic braking, rear hatch movement, and digital headlight beam problems.

1. 1
   Electrical system

   12V and 48V battery warnings with no-start episodes

   • 23 complaints (42%)
   • median 3,700 mi at 1.3 yrs old (2 state mileage, few)
   • 1 mention a crash, fire or injury
   • filed 2023–2026

   Owners report warning messages about the 12V or 48V electrical system on the instrument cluster, followed by the car refusing to start, shutting down while driving, or sounding alarms that will not stop. Some describe the vehicle being unusable for an hour or more before it restarted on its own, and some say it had to be towed. According to complaints, the dealer often found no fault or could not reproduce it, and the repairs described include a software update, a 48V battery replacement and a fuse box replacement. Mileage is recorded for only a few of these, from a few hundred to about 7,000 miles, and several describe problems in the first weeks of ownership.

   Recall 24V1150001 related service bulletin

   What to check: Ask whether the 48V battery fault message described in the service bulletin has been checked on the vehicle, and whether any software updates or battery and fuse repairs are documented. During a test drive, watch the instrument cluster for battery or electrical warnings and ask the dealer to scan for stored fault codes.

   2 excerpts from owner complaints in NHTSA records

   “The care sends a message that the battery is low. Then the check engine light comes on till we drive the car for awhile. The first time this happened I took it to the dealer and they said they could find nothing wrong with it and was giving no readings. It has continued to happen a lot. The battery should not be going down if it not being used. There has to be a problem. This has been going on for over a year. …”

   NHTSA complaint #11615647, filed 2024-09

   “When starting the vehicle, all the lights and alarms have come on and vehicle is not drivable. This has happened 4 times. 3/4 times the vehicle has started after an hour or two. One time I have had to have it towed in. I bought this car on April 27th. First time this happened was 5/29. I have been without the use of this car for 28 days today. The service manager called today and Mercedes is trying to fix the problem, they say it is happening to many people.”

   NHTSA complaint #11525409, filed 2023-06
2. 2
   Engine

   Check engine light that comes and goes

   • 15 complaints (27%)
   • median 400 mi at 0.8 yrs old (1 states mileage, few)
   • filed 2023–2024

   Owners describe the check engine light turning on while driving, sometimes going off on its own and returning later. According to complaints, dealers often found no error codes, cleared stored codes, or attributed the light to temperature, and some owners link it to 48V or 12V battery messages. Several describe repeated visits to the service department without a lasting explanation. Mileage is rarely recorded here, but several describe the light appearing early in ownership, within a few hundred to roughly 1,000 miles.

   What to check: Ask the dealer to read the stored fault codes and any freeze-frame data for the light, and whether a software update for the engine or battery electronics has been applied. Check the service history for repeated visits with no repair recorded.

   2 excerpts from owner complaints in NHTSA records

   “1.This is my new GLC 300 and after taking delivery and running for around 300 miles check engine light on my dashboard 2.Took it to Ray catena freehold service center and they kept this vehicle for 2 days and ran test and said no issues or no error codes found for the engine light 3. Service department said they cleared all the codes and updated the software and it should be good 4. After taking it from service center the check engine light is again on and its quite random 5. …”

   NHTSA complaint #11543740, filed 2023-09

   “Sunday, June 25, when I was driving the car on the road, the engine shut off and the car stopped running. 3 warning lights show on screen: engine light; 48v Battery Service Required; 12v Battery service required. I used the break to park the car on the roadside after that. I tried many times to restart the car, Waited over one hour and 40 minutes it finally started again, the engine warning light was still on until the second day morning, and I was able to take pics as evident. 1. …”

   NHTSA complaint #11529864, filed 2023-07
3. 3
   Forward collision avoidance

   Automatic braking or slowing without a clear hazard

   • 11 complaints (20%)
   • median 11,000 mi at 1.9 yrs old (2 state mileage, few)
   • filed 2023–2026

   Owners report the car braking hard or slowing sharply on open roads, when passing parked vehicles, or with no traffic nearby, sometimes after a warning beep. Some describe braking that could have led to a rear-end collision, and others say the car slowed after reading a speed sign for an exit ramp the car was not using. Other accounts describe the collision-assist alarm sounding, the seat belt tightening, and the brakes locking up. According to complaints, the dealer confirmed some events, and in some cases the vehicle was not repaired. Mileage is recorded for only a few of these, with the figure given at about 12,000 miles, and the speeds mentioned range from about 35 to 70 mph.

   What to check: During a test drive, ask about the automatic braking and speed-sign settings and whether they can be adjusted or turned off. Ask the dealer whether any software update for the driver-assist systems has been applied, and check the service history for related visits.

   2 excerpts from owner complaints in NHTSA records

   “Unknown: Driving on Route I 71 south in Cincinnati going CVG to pick up wife. 60-70 MPH. All systems normal.Suddenly out of blue , Brakes slam on 3-3 seconds seatbelt locks on and car deaccelerates with no warning , no lights , no registered failure. Belt compression severe, almost brushing strength. My wife has a spinal injury, cage in her neck ., must wear brace . …”

   NHTSA complaint #11551129, filed 2023-10

   “There are two issues 1) Unsure of the exact date, but about a year or two ago we were driving our car and the car's automatic break system went into effect on a typically busy, 3 lane road despite there not being any cars in front of our vehicle. We took it into the dealership, who confirmed the issue and told us that sometimes the automatic brake mis-identifies the metal plates in the roads to be vehicles. …”

   NHTSA complaint #11725254, filed 2026-03
4. 4
   Other or unknown

   Rear hatch or tailgate closing or opening on its own

   • 7 complaints (13%)
   • median 5,500 mi at 1.2 yrs old (2 state mileage, few)
   • 2 mention a crash, fire or injury
   • filed 2023–2025

   Owners describe the power hatch or tailgate moving without a clear command, including opening while the car is parked and closing while people or items are still at the rear. Reports describe the hatch closing onto a person's head or hands, and a driver being trapped in the rear. According to complaints, a dealer disabled the hands-free function. A service bulletin describes accidental activation of the key's tailgate button. Mileage is recorded for only a few of these, between about 1,000 and 10,000 miles, and the events happen during loading, unloading, or while the car is parked.

   1 related service bulletin

   What to check: During a walk-around, ask whether the hands-free or keyless tailgate function is enabled and test the hatch's reversal when it meets resistance. Ask whether the service bulletin on accidental tailgate button activation has been checked on the vehicle.

   2 excerpts from owner complaints in NHTSA records

   “When working in the rear cargo area, the door comes down without warning and does not break when it meets resistance trapping me between the body of the car and the descending door. A great deal of physical pressure must be employed in trying to get it to reverse direction. It is a struggle to get out from under the continually closing door. This has happend to me on three different occasions. There should be an automatic reversal when the door meets resistance not unlike a garage door.”

   NHTSA complaint #11591232, filed 2024-05

   “1. The rear hatch has opened while the car was left unattended. 2. If the hatch opens it could possibly cause a safety issue: a.By opening while driving. This has not happened and I do not know if Mercedes has a safety lock to ensure this could not happen. b.Open while parked and unattended. The vehicle would be unsecured with items being subjected to being stolen. c.Open while parked at the store, mall, etc. A stranger could get in the rear of the vehicle, close the hatch and wait for me to return causing a dangerous situation. …”

   NHTSA complaint #11530442, filed 2023-07
5. 5
   Exterior lighting

   Digital headlight low beam and adaptive beam complaints

   • 10 complaints (18%)
   • median 7,000 mi at 1.8 yrs old (1 states mileage, few)
   • 2 mention a crash, fire or injury
   • filed 2023–2024

   Owners say the digital headlights give a low beam that is too low or has dark, uneven areas, and that adaptive high beams sometimes drop to low beam without an apparent trigger. Some describe warning messages on the instrument cluster, the adaptive driving beam not working, cornering lamps not being activated, and beam problems in wet weather with condensation on the lamps. According to complaints, the dealer found nothing wrong and told owners to contact the manufacturer. Mileage is not recorded in these reports, and the complaints describe the problems at night or on unlit roads.

   Recall 25V365000

   What to check: On a night drive or in a dark area, check the low beam and adaptive high beam behavior and whether any headlight warning messages appear. Ask whether the headlight recall for this model year, which concerns headlight adjustment caps, applies to the vehicle.

   2 excerpts from owner complaints in NHTSA records

   “DIGITAL LIGHT low beam inadequate distance for safe driving on unlit roadway. Low beam has unnecessary blacked out areas causing distraction. Low beams too low, especially driving down hills. Adaptive high beams revert to low beam without any apparent light to trigger camera/sensor. Dealer states they are all the same, nothing they can do, call MB USA. MB USA gave me a case number but do no seem interested in solving the issue”

   NHTSA complaint #11539552, filed 2023-08

   “The moon roof will not close. There is also a sloshing sound of water in an unidentified area, it has not rained. The blind spot monitor function of the digital light projection works intermittently and is barely visible marking on the roadway. The exit assist also does not activate the ambient lighting when opening door and car Is approaching in the travel Lane. Digital lights have jagged output light beam and they are the illuminating the roadway as advertised.”

   NHTSA complaint #11536675, filed 2023-08

Buying note. For someone considering this model year, the complaints point to checking the electrical warning history, asking whether battery, fuse, and software repairs are documented, and testing the automatic braking, hatch, and headlight functions on a test drive. Mileage and dealer records help show whether a symptom returned after a repair.

Summary written with AI from a sample of 49 NHTSA complaints for this model year (picked at random, with complaints that state a mileage and recent ones taken first), then checked automatically against the source records. Where a problem shows a complaint count, every complaint for this model year was matched with fixed keyword rules (written with AI and tested against the sample), and the mileage, age and repair figures are calculated from those complaints; owners' figures are as stated, not verified. Other counts refer to the sample. The excerpts come from NHTSA's public complaint records and are unverified; capitalisation is normalised, NHTSA staff notes are removed, and shortened text ends with “…”. Something wrong? Request a correction.