What component or system failed or malfunctioned, and is it available for inspection upon request? The Forward Collision Avoidance / Active Brake Assist (Automatic Emergency Braking) system failed by falsely identifying a non-existent threat and initiating uncommanded emergency stopping. The vehicle and its onboard control modules are fully available for physical and diagnostic inspection upon request. How was your safety or the safety of others put at risk? While traveling at approximately 35 mph, the vehicle suddenly executed maximum emergency braking with zero warning and no preceding obstacles, vehicles, pedestrians, or road hazards present. The violent deceleration caused maximum seatbelt restraint locking force, resulting in sudden physical impact trauma to a 6-month pregnant passenger and acute dizziness/disorientation for both occupants. This malfunction creates a severe, immediate risk of high-speed rear-end collisions from trailing traffic and unexpected loss of vehicle control. Has the problem been reproduced or confirmed by a dealer or independent service center? Not yet. The vehicle has not yet been serviced or inspected by a dealer or independent service center following this event. Has the vehicle or component been inspected by the manufacturer, police, insurance representatives or others? No. Neither the manufacturer, police, insurance representatives, nor third-party investigators have inspected the vehicle or component since the incident occurred. Were there any warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear? There were no warning lamps, error messages, chime alerts, or functional symptoms prior to the sudden brake activation. The Active Brake Assist system triggered immediately without prior warning.
Mercedes-Benz GLC 300 seat belt problems
19 of the 665 owner complaints about the Mercedes-Benz GLC 300 describe seat belt won't latch or retract, most of them for the 2017 model year.
- owner complaints
- 19
- worst model year
- 2017
- typical mileage
- 29,750
By model year
Often reported together
What owners say
A message that passenger air bag is damaged/will not deploy appears. Passenger seat belt gets stuck and cannot be opened. Check engine light on-pvc valve issue most likely.
I purchased a brand new GLC 300 on May 25, 2023. By June 2, 2023 I was already stranded due to a 12V battery electrical system failure. Since then I have been stranded 8 total times and the vehicle has been in the service department 14+ times for repeated electrical issues (8 of those visits were related to the same 12V battery electrical system failures. The battery was reportedly replaced in 2024-shortly thereafter I began experiencing issues with the collision assist malfunctioning. The alarms would sound seat belt tighten and brakes lock up while driving on the interstate. The theft deterrent alarm wound sound in the middle of the night without provocation. The panoramic roof would malfunction. The air vent disintegrated. In August 2025, the collision assist malfunctioned causing the vehicle to steer off the road resulting in a blow out. It has not been driven since.
The contact owns a 2017 Mercedes-Benz GLC300. The contact stated that while parked and attempting to release the seat belt, the seat belt remained latched. The contact stated that after the third attempt, the seat belt operated as needed. The failure had occurred in the front driver’s and passenger’s side seat belts. The vehicle was taken to a dealer, where it was determined that the buckle and needed to be replaced. The seat belt buckle was replaced, and the vehicle was repaired. The manufacturer was notified of the failure but offered no assistance because the warranty had expired. The approximate failure mileage was 71,000.
The contact owns a 2025 Mercedes-Benz GLC300. The contact stated that while driving approximately 30 MPH, there was an abnormal grinding sound coming from the vehicle. The contact stated that the brake assist suddenly activated and the vehicle came to an abrupt stop, causing the seat belt to immediately retract and lock. The contact was slightly jerked from the abrupt stop. The contact stated that a warning light with a red triangle with an image of a crash in the center was illuminated. The contact stated that after starting the vehicle, the infotainment center and the instrument panel were completely black. The vehicle was restarted several times before both systems started operating as needed. The failure occurred twice; however, the second time, the contact had to turn off and restart the vehicle for approximately an hour before the infotainment center and instrument panel became operational. The vehicle was taken to the dealer, who performed a software update for the infotainment center. After the software update was completed, the contact became aware there were other electrical systems that failed intermittently, including the voice activation system. The vehicle was returned to the dealer and the contact was informed that the front driver’s and passenger’s sides sensors were too low and there was no reason for the notification to become activated. The vehicle was not diagnosed or repaired. The manufacturer was informed of the failure, and a case was opened. The failure mileage was approximately 2,000.
No incident my vehicle has a front left malfunction service required light and issues with the passenger seatbelt not proper latching. Upon checking I notice my car had previous recalls done. It seems as if the same issues has come about. the federal safety agency: 18v177- seat belt not retracting properly. the federal safety agency: 17V627 is related to the steering column switch replacement of clock spring. So if me or a family member was to get into an accident no airbag will deploy! Huge safety hazard!
The contact owns a 2017 Mercedes-Benz GLC300. The contact stated that while driving on several occasions at various speeds, the front passenger’s side seat belt retractor failed to extend or retract as intended and became stuck. The vehicle was not diagnosed or repaired. The manufacturer was not notified of the failure. Additionally, the contact stated that on several occasions while started and running, the message “Service Soon” was displayed. The vehicle was taken to a dealer where it was diagnosed and determined that the clock spring needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was approximately 120,000.
The contact owns a 2018 Mercedes-Benz GLC300. The contact stated that when the driver's side seat belt was buckled, the seat belt alarm chimed as if the seat belt was not buckled. The contact had to buckle and unbuckle the seat belt several times before the warning chime stopped. The contact had taken the vehicle to a local dealer who diagnosed the vehicle and determined that there was no issue with the seat belt system. The vehicle was not repaired. The contact stated that the failure was intermittent. The contact researched online and related the failure to the federal safety agency Campaign Number: 19V788000 (Seat Belts) however, the model year was not included. The manufacturer was informed of the failure. The failure mileage was approximately 48,000.
Rear seat belt latch plates (both driver and passenger side) retracted into the rear side paneling behind the seat. Both seat belts are now unusable. Issue occurred after rear seats were folded flat and then returned to upright position. Vehicle does not have dynamic locking tongue latch plates in the rear seats. MB dealership and MB customer care both claim that vehicle is not under the federal safety agency recall 18V‑177 despite fitting the issue description, make & model, and production date.
The seat belt latch in the second seating row, the outboard seatbelt latch plate retracted into the area between the c-pillar paneling and the rear side paneling. The rear occupant was not be able to fasten the seat belt latch. The latch plate retracted behind the panel and the seat belt for the affected rear seat was not be available for fastening. I was able to grab the latch plate with a pliers and bring it out from behind the panel but I am afraid this situation will occur again. I checked my VIN against you checker and it says NO RECALL is pending. I assume MB did not include this VIN in its report to you or falsely claimed the vehicle was repaired. reference # 2018030012, May 2018
Related recalls
Seat belts: rear/other
- What is wrong
- Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2026 AMG GLC43 4MATIC, GLC 300 4MATIC, GLC 300, and GLC 300 4MATIC Coupe vehicles. The center rear seat belts may have been installed without the child seat protection function and fail to lock a child restraint properly. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 208, "Occupant Crash Protection," and FMVSS number 209, "Seat Belt Assemblies."
- Risk
- In the event of a crash, an insufficiently restrained child has an increased risk of injury.
- Remedy
- Dealers will inspect and replace the center rear seat belt assembly as necessary, free of charge. Owner notification letters were mailed May 15, 2026. Owners may contact MBUSA customer service at 1‑800‑367‑6372. Vehicle Identification Numbers (VINs) involved in this recall will be searchable on beginning March 27, 2026.
Recall number 26V172000 · Recall details
Seat belts: pretensioner
- What is wrong
- Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2021 C-Class, E-Class, E-Class Coupe and Convertible, GLC, CLS, AMG GT 4-door Coupe and G-Class vehicles. Please refer to MBUSA's recall report for specific vehicle model details. A faulty electrical contact within the seat position switch may prevent the driver and passenger air bags and seat belt force limiters from properly activating during a crash.
- Risk
- Air bags and seat belts that do not perform properly in a crash can increase the risk of injury.
- Remedy
- MBUSA will notify owners, and dealers will replace the seat position switches, free of charge. Owner letters were mailed May 21, 2021. Owners may contact MBUSA customer service at 1‑800‑367‑6372. MBUSA's number for this recall is 2021040016.
Recall number 21V230000 · Recall details
Seat belts
- What is wrong
- Mercedes-Benz USA, LLC. (MBUSA) is recalling certain 2018 E400 Wagon 4MATIC, E400 4MATIC, E43 AMG 4MATIC, 2018-2019 E63S AMG 4MATIC Wagon, E63 AMG 4MATIC Wagon, E300, E300 4MATIC, GLC63S Coupe AMG 4MATIC, 2019 CLS450, CLS450 4MATIC, CLS53 AMG 4MATIC, E450 Wagon, E53 AMG 4MATIC, GLC300, GLC63 AMG Coupe 4MATIC, G550 4MATIC, G63 AMG, GLC300 Coupe 4MATIC, GLC300 4MATIC, GLC350e 4MATIC, GLC43 AMG Coupe 4MATIC, GLC43 AMG 4MATIC, GLC63 AMG 4MATIC, GT63 AMG four-door 4MATIC, and GT63S AMG four-door 4MATIC vehicles. Although correctly fastened, the front seat belts may be inaccurately detected as being unfastened, which may cause the electric PRE-SAFE®-function and the pretensioner to be deactivated.
- Risk
- The electric PRE-SAFE®-function and the seat belt pretensioners may not deploy during a crash, increasing the risk of injury.
- Remedy
- MBUSA will notify owners, and dealers will inspect the front seat belt buckles, replacing them as necessary, free of charge. The recall began March 13, 2020. Owners may contact MBUSA customer service at 1‑800‑367‑6372. MBUSA's number for this recall is 2020020017.
Recall number 19V788000 · Recall details
Seat belts: rear/other: buckle assembly
- What is wrong
- Mercedes-Benz USA, LLC. (MBUSA) is recalling certain 2016-2018 Mercedes-Benz GLC300 and GLC300 4Matic, 2018 GLC350e and GLC63 AMG 4Matic and 2017-2018 GLC43 AMG 4Matic vehicles. The seat belt latch plates (the parts that insert into the buckles) for the outboard rear seats may retract into the interior paneling, preventing the occupants from being able to use the seat belts.
- Risk
- If the rear seat passengers cannot fasten their seat belts, they have an increased risk of injury in the event of a crash.
- Remedy
- MBUSA will notify owners, and dealers will install felt strips between the C-pillar and rear side paneling, free of charge. The recall began November 2, 2018. Owners may contact MBUSA customer service at 1‑800‑367‑6372. MBUSA's number for this recall is 2018100002.
Recall number 18V683000 · Recall details
Seat belts: rear/other: buckle assembly
- What is wrong
- Mercedes Benz USA LLC (MBUSA) is recalling certain 2017-2018 GLC43 AMG, 2016-2018 GLC300 4Matic, 2016-2018 GLC300, 2018 GLC63 AMG 4Matic, and 2018 GLC350e 4Matic vehicles. The seat belt latch plates (the parts that insert into the buckles) for the outboard rear seats may retract into the interior paneling, preventing the occupants from being able to use the seat belts.
- Risk
- If the rear seat passengers cannot fasten their seat belts, they have an increased risk of injury in the event of a crash.
- Remedy
- MBUSA will notify owners, and dealers will install a buffer to the c-pillar paneling, free of charge. The recall is expected to begin May 14, 2018. Owners may contact MBUSA customer service at 1‑800‑367‑6372. MBUSA's number for this recall is 2018030012.
Recall number 18V177000 · Recall details
Seat belts: pretensioner
- What is wrong
- Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2017 C300, C300 4Matic, C300 Coupe, C300 Coupe 4Matic, C43 AMG, C43 AMG Coupe, C43 AMG Cabrio, C63 AMG, C63 AMG Coupe, C63S AMG, C63S AMG Coupe, C63S Cabrio, GLC300, GLC300 4Matic, GLC43 AMG, S550, S550 4Matic, S550e, S600, S63 AMG 4Matic, S65, Mercedes-Maybach S550 4Matic, and Mercedes-Maybach S600 vehicles. The affected vehicles have front seat seatbelt pretensioners that may not function properly in the event of a crash. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 208, "Occupant Crash Protection," and 209, "Seat Belt Assemblies."
- Risk
- If the front seat seatbelt pretensioners do not function properly, the seat occupants may not be adequately restrained in the event of a crash, increasing the risk of injury.
- Remedy
- MBUSA will notify owners, and dealers will replace the front seat belts, free of charge. The recall began October 13, 2017. Owners may contact MBUSA customer service at 1‑800‑367‑6372.
Recall number 17V251000 · Recall details
Questions about the Mercedes-Benz GLC 300 seat belt
Which Mercedes-Benz GLC 300 years have seat belt won't latch or retract problems?
The model years with the most reports are 2017 (6 complaints), 2018 (6 complaints) and 2016 (2 complaints).
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