2020 Mercedes-Benz GLC 300

On January 8, 2021, after ongoing review with Mercedes Benz, the National Highway Traffic Safety Administration (NHTSA) Office of Defects Investigation (ODI) opened PE21-001 to assess allegations of front roof panel detachments while driving at highway speeds in certain 2015 Mercedes-Benz (Mercedes) C-Class vehicles.The subject front roof panel is a stationary panel composed of polycarbonate and is attached to the vehicle via adhesive at the time of manufacture. The panel is found on subject vehicles equipped with panoramic sunroofs. Over time, the subject panels may exhibit cosmetic degradation leading to replacement of the panel, a procedure which entails: removal of the old panel and adhesive, site preparation, and installation of a replacement panel with new adhesive.The consumer complaints that prompted the opening of PE21-001 all described detachments of front roof panels that had been replaced after the vehicle was put into service.Mercedes' internal investigation identified a broader scope of affected vehicles (2014-2020 CLA, GLA, C, S, GLC, and GLE class) and found the following potential service procedure- related causes of front roof panel detachments:- Improper surface pretreatments such as the use of the wrong primer or cleaner or scoring of the surface; or - Use of the incorrect adhesive.These conditions lead to a front roof panel bond that, even if sound at the time of repair, cannot maintain its strength over time and environmental exposure.Mercedes updated its service and parts ordering systems to reinforce the proper use of specified kits and procedures via webinars, shop foreman meetings, and explicit reference to the risks incurred by diverging from the repair procedures. Mercedes is also furnishing parts ordering assistance, and will hold dealerships accountable for improper repairs.ODI's analysis of the ten complaints it has received from the public (VOQ's) and MBUSA's complaint data submitted in response to the information request letter for PE21-001 identified a total of 57 non-duplicative reports alleging incidents in which the front roof panel detached from the vehicle while in motion. Included within the 57 reports are incidents where consumers state the panel detached ...and flew off into traffic.On March 19, 2021, Mercedes notified NHTSA that it would recall subject vehicles with front roof panels known to have been replaced after the original sale of the vehicle. In total, the recall (designated as Recall 21V197) covers 15,099 vehicles that were ever registered in the United States. Based on Recall 21V197 and the remedy implemented by Mercedes, further investigation does not appear to be warranted at this time.Accordingly, this investigation is closed.The ODI complaints cited above can be viewed at www.nhtsa.gov under the following ODI identification numbers: 11376425, 11352686, 11351629, 11349158, 11341541, 11337594, 11324100, 11311591, 11222127, 11404183

My check-engine light recently illuminated, and diagnostic testing identified fault code P06DA00, relating to the oil pump control valve circuit. I have been quoted over $5,000 to replace the oil control valve and oil pump harness. I was quoted the following by Mercedes Servuce in Manchester, NH- Oil Pressure Regulator Valve: need to remove lower oil pan only to access oil control valve and replace the valve and sub harness. $5013.52. This is a known issue. My vehicle has been well maintained, and I have been advised that it is otherwise in excellent mechanical condition. I intend to keep and drive this vehicle for many more years, which makes it particularly disappointing to encounter a repair of this magnitude for a component that is not considered a routine maintenance or wear item.

NHTSA ID

11761172

Incident

Jul 28, 2026

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.

NHTSA ID

11760501

Incident

Aug 28, 2026

My 2020 Mercedes-Benz GLC 300 triggered check engine light with code P06DA (engine oil pressure control) at 40,000 miles. The failed component is an oil pressure control sensor/solenoid worth approximately $200. However, due to Mercedes-Benz's engine design (M264 engine), the entire engine must be removed from the vehicle to access and replace this part. Repair estimate from authorized Mercedes-Benz dealership (Mercedes-Benz of Stevens Creek): $8,391. SAFETY CONCERN: Loss of oil pressure can cause catastrophic engine failure while driving. Engine seizure at highway speeds poses serious risk of loss of vehicle control, potential accident, and harm to occupants and other drivers. This is a known, widespread design defect affecting Mercedes-Benz vehicles equipped with M264/M274 engines across multiple model lines: GLC 300 (2019-2023) C 300 (2019-2023) E 300 (2019-2023) GLC 43 AMG, C 43 AMG GLB 250, A 220, CLA 250 Mercedes-Benz's own authorized dealership confirmed they are "seeing this issue more and more." Despite awareness of this widespread defect, Mercedes-Benz has not issued a recall or Technical Service Bulletin. The design makes repair financially prohibitive ($8,000+), meaning many owners continue driving with compromised oil pressure — creating an ongoing safety hazard on public roads. Mercedes-Benz refused to repair under goodwill, then denied repurchase after 30-day review. They have left consumers with no remedy for a known safety-related design defect. I am requesting NHTSA investigate this as a safety defect affecting potentially hundreds of thousands of vehicles.

NHTSA ID

11746524

Incident

May 4, 2026

I have had my car for almost two years. This problem has been on-going the whole time. It happens intermittently, I never know. I will be driving it and usually when I am making a turn or pulling onto a main road, you press the gas to go and the car hesitates and makes a loud brooooooooom sound like it is trying to go or figure out what to do and if you are pulling out onto a main road with on comming traffic, this is dangerous. We have seen information that on the 2019 and 2018 GLC300's this has been documented, my car is a 2020 but it's the same thing. It's like the car hesitates and slows down when it should go!

NHTSA ID

11737705

Incident

Jun 23, 2024

There was a recall on headlight leaking and this happened to my left headlight no damage but leaking and this caused headlight to not work

NHTSA ID

11719167

Incident

Feb 10, 2026

The contact owns a 2020 Mercedes-Benz GLC300. The contact stated that while driving at an undisclosed speed, the panoramic roof unexpectedly shattered. There was no warning light illuminated. The vehicle was taken to the dealer, where it was determined that the panoramic sunroof and the sunroof protector needed to be replaced. The vehicle was not repaired. The manufacturer was made aware of the failure, and a case was opened. The approximate failure mileage was 53,035.

NHTSA ID

11715247

Incident

Feb 3, 2026

Mileage

53,035 mi

Premature oil pump failure on a 2020 Mercedes-Benz GLC 300 with 71,000 miles. The check engine light illuminated on December 29th, 2025 and with no other warning symptoms. The vehicle has been maintained properly, including regular visits to Mercedes-Benz dealerships. The oil pump is a critical engine component that should not fail at this mileage. It has been recommended to not drive the vehicle without repairing as oil can leak onto a hot engine. This issue has been confirmed by a Mercedes dealer. Mercedes-Benz has offered $1,000 in goodwill on a $7,400 repair, which is unreasonably low given the nature of the failure. The dealer is advocating for higher goodwill, but corporate has refused to escalate or provide a breakdown of the offer. This failure appears to be a premature mechanical defect rather than normal wear, and I am filing this complaint to request federal tracking and review.

NHTSA ID

11712746

Incident

Dec 29, 2025

Water condensation within the driver side headlight which caused the complete headlight unit, control unit, and module to fail. This is a huge safety issue due to unable to operate vehicle safely during the when it comes to making left turns due to no signal indicator and a safety issue/hazard when driving at night. The issue has been inspected with a local dealer and with corporate being aware of the manufacturer defect. There were no indicators nor warning lamps prior to this issue.

NHTSA ID

11711256

Incident

Dec 27, 2025

Complaint During part of the steering movement, it feels heavier or more difficult to steer in the same spot every time. OR Rattling, humming, dry sliding/gravel noise from the electric steering system when steering (see attachment). Complaint does not impact the ability to safely steer or control the vehicle. Cause Ball screw drive (KGT) of electric steering damaged by: 1. External force due to: ‑ Hitting the curb/posts with the front wheels. ‑ Driving over obstacles (e.g. pothole/ threshold/ speed bump/ gully) at an inappropriate speed. 2. Corrosion/ water ingress through a damaged boot (see attachment). ‑ Cracks (1) ‑ High pressure cleaner (2) ‑ Animal bite (3) See various examples listed in the attachments for examples of outside influence. Remedy Remove boot clamps closest to steering gear housing on both left and right (as seen in "Steering Rack Boot Clamp Location"). Pull back boot and inspect for rust, broken end stops, water, or any other anomalies. Replace electric steering. Note: Steering gears replaced due to outside influence or damage must not be claimed under warranty!

Complaint Tailgate opens unintentionally. Cause Accidental or unnoticed activation of the button to open the tailgate on the vehicle key. EXAMPLE: when stored in trouser pocket, handbag etc. Remedy As of the 6th generation, the vehicle key can be recoded so that the tailgate no longer opens as a result of a long press on the button, but by double‑clicking on the button instead. This reduces the likelihood of the button being activated accidentally or unintentionally. The recoding can be carried out as follows: 1. Add SA Code O19 into VeDoc (O for Oscar, not "zero") • an XSS ticket may be necessary to add the SA code 2. Perform SCN coding of EIS N73 control unit 3. Deactivate the vehicle key (a successful deactivation is indicated by the LED lighting up 2x briefly and then 1x for a long period). 4. Place the vehicle key in the storage compartment on the key symbol and turn on the ignition. IMPORTANT: all other vehicle keys must be outside the recognition range of the vehicle when doing this! Perform steps 3 and 4 successively for all vehicle keys. Notes: 6th, 7th and 8th generation keys can be deactivated as follows: Up to modification year 22/1 by double clicking the "Lock button" As of modification year 22/1, by press and holding the “Lock button", then double‑click the “Unlock button" at the same time. On model series 167, the storage compartment with the key symbol is located in the armrest. The SCN coding from the EZS is only transferred correctly to the vehicle key under the following conditions: Only one vehicle key is located in the vehicle, this key has been deactivated and it is positioned on the marking in the storage compartment for the data transfer. The costs for this adaptation are to be borne by the customer. For the newer BR 174, 178, 244, 248, 520, and 540, a software update must be initiated, as there is no way to perform SCN coding.

Dear Mercedes-Benz Owner: In our continuing efforts to ensure the proper performance of Mercedes-Benz products and to enhance the satisfaction of our customers, Mercedes-Benz USA is extending the warranty coverage for the Diagnostic Module for Tank Leakage Detection ("DMTL") on your vehicle from the original New Vehicle Limited Warranty of 4 years / 50,000 miles to 15 years/150,000 miles (whichever occurs first). This applies to the vehicle regardless of ownership. Why the Warranty extension? On certain Model Year 2018 - 2024 A / C / CLA / CLS / E / G / GLA / GLB / GLC / GLE / GLS / GT / S / SL Mercedes-Benz vehicles, under certain circumstances, the DMTL may trigger erroneous Diagnostic Trouble Code ("DTC") entries that may result in the illumination of the Check Engine Malfunction Indicator Lamp ("MIL"). Any repairs under this warranty extension must be performed by an authorized Mercedes-Benz dealership. • If your preferred authorized Mercedes-Benz dealership performs a diagnosis and confirms that your vehicle has the issue, the repair will be covered under this extended warranty and performed at no cost to you. • This extended warranty does not apply to any other components or conditions beyond the ones mentioned above, and standard warranty terms apply, including the exclusions with respect to extra expenses, as identified in the Service and Warranty Information booklet.

Complaint 1. General Diagnostic Tips 2. One or More PARK Sensor Activations 3. Red Ring Around Vehicle 4. "Active Parking and Parking Assist Inoperative" on Instrument Cluster 5. Cameras 6. Other Park Topics. Cause Various root causes Remedy See attached diagnostic guide.

Complaint A popup is seen on the HU with the message "data connection temporarily not available". Potentially affected functionalities in NTG4.5, NTG5 1.Weather 2.Local Search 3.IP Radio 4.Send2Car 5.Speech Detection Service 6.Navigation 7.iHeartRadio 8.Traffic Cams Cause MB Apps is sundowned for all vehicles with NTG4.5 and NTG5 Head Unit Variant. Remedy No support available for NTG4.5 and NTG5 Head Unit Variants for MB App related topics. Note: Please do not create TIPS. Please do not replace any components. HU/Hermes SW update / SCN coding will not fix the issue.

Complaint Clanking noise from the area of the speakers in the doors. Cause Under analysis. Remedy To narrow down the cause, first of all remove the door trim. • If the noise continues to occur even with the door trim removed, then continue the diagnosis working towards the speaker and if necessary, create a TIPS case with an informative video as an attachment. Information: Please refer to this document in the warranty claim and, after completing diagnosis, select the damage code corresponding to the component part that caused the problem. • If the noise stops when the door trim is removed, please proceed in accordance with LI72.10-P-067691. Information: In this case, do not use a damage code for the speakers in the warranty claim!