2018 Mercedes-Benz GLC 300 Electrical Problems

Safety Issue: Infotainment display screen produces scrambled pixels during Apple CarPlay navigation while driving. Description: When Apple CarPlay is connected and navigation is in use, the vehicle's infotainment display screen suddenly produces scrambled pixels, rendering the map and display unreadable. This malfunction occurs without warning while the vehicle is in motion, creating a dangerous visual distraction for the driver and uncertainty of where and when to turn or exit. This is a known, recurring issue. On January 7, 2021, I brought this problem to Mercedes-Benz of Indianapolis (Repair Order #624027), where a firmware update was applied and the issue was allegedly resolved. The fix has not proven permanent — the problem has since recurred and continues to present a safety hazard while driving. Despite this being a widely documented issue affecting numerous Mercedes owners, Mercedes-Benz has not issued a recall or technical service bulletin that I am aware of. My dealer is requiring a diagnostic fee of over $250 to inspect the vehicle, and Mercedes-Benz USA customer service has been unreachable. Requested Action: I am requesting that NHTSA investigate this issue and consider whether a Technical Service Bulletin or recall is warranted given the safety implications of a sudden display malfunction while driving.

NHTSA ID

11732752

Incident

Jan 1, 2026

I had the engine light come on and took it to the dealership. They quoted me over 8 thousand dollars to fix. I took it to a repair shop that works on luxury cars and they fixed it for less than 1000 dollars. I had to have the transducer fixed in the turbo in my engine and when they did that they found oil in the electrical harness. That was caused by the oil seperator. They told me that it was a manufacture defect that has been well documented and to take it back to Mercedees Benz. They looked and found the oil but said my car did not produce a code and could not fix it. We escalated it to corporate that reviewed my case and said they still would not fix until it produced a code. Mercedees implemented an extended warranty for my car back in 2022 for emissions. They said they would cover it if it produces a code. I researched this problem and it said it posses a risk to me, my passengers and the public if it quits running or causes a fire. Corporate said its not a problem yet.

NHTSA ID

11698021

Incident

Oct 15, 2025

I brought my vehicle in to get serviced because the check engine light came on and I was told it was CODE PRESENT P0521E71 VALVE FOR CRANK CASE VENT. HAS MALFUNCTION / BLOCKED. I was told I have warranty on it so Mercedes of Massapequa took the car to fix.I was told the part was fixed but oil was found on my engine computer from the crank case vent malfunctioning but the warranty won't cover it although it was a direct result of a part that was covered part and had caused the damage.They gave me my car back and my car is worse it has problems starting it requires multiple cranks and the air conditioner has a fuel smell when turned on and I am unable to pass my vehicle inspection because my check engine light it still on.I spoke to the corporate office and they said because I have too many miles they can't do a courtesy and honor the cost and referred me back to the dealer and the dealer told me they will bring the cost to fix the computer leak to $6000 although it was due to a faulty part on their behalf .I am beyond upset my car is non longer reliable or safe to drive.Mercedes of massapequa ignored all my calls after they gave me back my vehicle that was worse after they claimed they fixed it.

NHTSA ID

11579424

Incident

Nov 6, 2023

The windshield washer pump failed due to the Sam unit. Failing I was in the mountains, started my car the windshield wiper malfunction light came on the wipers worked for a minute, so I turned them off, drove over the pass and tried to use my wipers, and they did not work. The back wipers did work. I took my car to my mechanic in Cheyenne, who discovered that’s the SAM unit Ruined the windshield washer pump. No one else has inspected it other than my mechanic. I have learned that there are others complaining of the same issue online. This is a dangerous issue when you are driving in a storm with no windshield wipers. My mechanic believes this should be a recall issue, and so do I. The Mercedes dealership said my mechanic, a faulty Sam unit to replace the Sam unit that went out. Now my car is throwing all kinds of codes and the back windshield wipers do not work.

NHTSA ID

11577478

Incident

Feb 15, 2024

Backup Camera randomly power cycle while the transmission is in REVERSE. It was listed for recall for 2019-2021 models vehicle and it has showed up in my 2018 GLC 300. Contacted Dealer multiple times and was told software update would have fix it. Left the vehicle with dealer multiple times and each time was told software update has been performed per manufacturer instruction. Yet the problem continue. When the incident happen, the camera screen went back to multimedia/radio/navigation screen, and the camera screen came back on. During that time, i can hear the camera pop in and out of the rear hatch (where the camera is located). it is a safety concern and definitely need a closer look at it.

NHTSA ID

11552656

Incident

Oct 28, 2023

Vehicle is switching gears automatically from Drive to Neutral in the middle of the road, in the middle of driving, VERY dangerous situation. I cannot put in reverse sometimes it switches back to N. . It always switch his back to neutral. Thankfully no accidents. Don’t know what to do?

NHTSA ID

11544396

Incident

Sep 7, 2023

All of the buttons on my steering wheel including the horn stopped working. I hear a clicking noise when i turn the steering wheel and the passenger air bag light randomly goes on and off. This leads me to believe the clock spring is broken. If the clock spring is the problem, this could create an airbag malfunction causing it to not deploy when needed or randomly deploy while i’m driving.

NHTSA ID

11535378

Incident

Jul 21, 2023

Vehicle stopped while driving on road. Car show "active brake assist malfunction" on the dashboard, immediately following the car will not accelerate. Shut the car off and restart, then the "check engine light" comes up. The active brake assist does not come up again, but the check engine light states on. I have taken the vehicle 5 times for this issue to the dealer, car is currently at the dealer. Reason of my report, is that I consider this situation extremely dangerous and should be investigated further. [XXX] INFORMATION Redacted PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6).

NHTSA ID

11525173

Incident

Mar 8, 2023

While driving my SUV, I turned a corner and I heard and felt a wire or wires pull and snap inside the steering wheel. I then found that I could not operate any of the controls on the steering wheel and the driver side airbag light came on with a disabled message on the display. I think that it is the clock spring inside of the steering wheel that got caught up and snapped from me turning the wheel.

NHTSA ID

11475794

Incident

Jul 2, 2022

WHEN I WAS PULLING INTO A PARKING SPOT AT A LOW SPEED, THE CAR ACCELERATED AND LURCHED FORWARD, HITTING A WALL, WHICH DEPLOYED THE AIRBAGS. WHEN THE CAR STARTED TO ACCELERATE, I HIT THE BRAKES BUT THEY DID NOT ENGAGE.

NHTSA ID

11349114

Incident

Aug 1, 2020

Mileage

21,000 mi

THE STEERING COLUMN STALK CONTROLS DRIVE, REVERSE, NEUTRAL AND PARKING. I STOPPED THE VEHICLE ON AN INCLINE IN A PARKING LOT. I HAD MY FOOT ON THE BRAKE. I SHIFTED INTO NEUTRAL. THE ENGINE WAS STILL RUNNING. I THOUGHT I PUSHED THE PARK BUTTON BUT THE CAR ROLLED BACK INTO ANOTHER VEHICLE.

NHTSA ID

11144554

Incident

Aug 14, 2018

Mileage

3,200 mi

'THE FIRST INCIDENT - OCCURRED IN AUGUST WHEN I STOPPED AT A STOP-LIGHT. I STARTED DRIVING WHEN THE LIGHT TURNED GREEN AND THE CAR WAS ACCELERATING AS NORMAL. THERE WERE CARS BEHIND ME ACCELERATING AS WELL AS NORMAL. MY SUV AUTOMATICALLY SHIFTED FROM DRIVE TO NEUTRAL BY ITSELF AS I CONTINUE TO ACCELERATE TO MOVE WITH THE NORMAL FLOW OF TRAFFIC. THE VEHICLE AUTOMATICALLY SLOWED DOWN TO NEUTRAL '2ND INCIDENT - THE SAME ISSUE OCCURRED AGAIN WITHIN TWO WEEKS I WAS DRIVING ON THE LONG ISLAND EXPRESSWAY AT APPROXIMATELY 40 MILES PER HOUR IN HEAVY TRAFFIC WHICH HAD COMMERCIAL TRUCKS. THE VEHICLE AUTOMATICALLY SHIFTED FROM DRIVE TO NEUTRAL ON ITS OWN. THIS NEARLY CAUSED A PILE UP ON THE LIE WITH THE CAR IMMEDIATELY BEHIND ME RUNNING INTO THE BACK OF MY CAR. '3RD INCIDENT - I STOPPED AT A STOP SIGN WAITING FOR THE LIGHT TO TURN GREEN IN ORDER TO MAKE A RIGHT TURN. I MADE A RIGHT ON VERY BUSY STREET AND THE CAR STARTED SHUTTING DOWN AND DECELERATING INSTEAD OF ACCELERATING. I URGENTLY STEERED THE CAR OVER TO THE SIDE OF THE ROAD AND TURNED IT OFF. I WAITED FOR A FEW MINUTES AND RESTARTED THE CAR AND IT SEEM TO HAVE BEEN WORKING. '4TH INCIDENT - ON SUNDAY SEPTEMBER 18TH, THE VEHICLE COULD NOT START SO I HAD TO CALL MERCEDES BENZ ROADSIDE ASSISTANCE. THE ENGINE DIDN'T MAKE ANY ATTEMPT TO START. THE LIGHTS DIDN'T TURN ON. THERE WAS ABSOLUTELY NO RESPONSE TO A KEYLESS OR MANUAL START. 'SEPTEMBER 29TH ' I PICKED UP THE SUV AND IT DROVE WELL WITHOUT ANY INCIDENTS 'OCTOBER 1ST ' THE VEHICLE AUTOMATICALLY SHIFTED FROM DROVE TO NEUTRAL AFTER MAKING A RIGHT TURN ON A VERY BUSY STREET WHICH NEARLY CAUSED AN ACCIDENT WITH ANOTHER CAR HITTING ME IN THE REAR. THIS NEARLY CAUSED A 'PILE UP' BECAUSE OTHER CARS WHERE URGENTLY SLAMMING THEIR BREAKS BEHIND ME TO PREVENT FROM HITTING THE CAR IN FRONT OF THEM. I WAS DROPPING MY SON OFF TO SCHOOL AND HE WAS SITTING IN THE BACK SEAT.

NHTSA ID

11140717

Incident

Oct 1, 2018

Mileage

6,000 mi

TL* THE CONTACT OWNS A 2018 MERCEDES-BENZ GLC300. THE CONTACT STATED THAT THE VEHICLE DOORS AUTOMATICALLY LOCKED WITH THE KEYS INSIDE OR OUTSIDE OF THE VEHICLE. THE VEHICLE WAS TAKEN TO MERCEDES-BENZ OF ALEXANDRIA (200 S PICKETT ST, ALEXANDRIA, VA 22304, (703) 341-2100) FOR DIAGNOSTIC TESTING AND REPAIRS. THE MANUFACTURER WAS MADE AWARE OF THE FAILURE VIA EMAIL. THE FAILURE MILEAGE WAS 6,124. THE VIN WAS NOT AVAILABLE.

NHTSA ID

11113400

Incident

Mar 24, 2018

Mileage

6,124 mi