2020 Mercedes Benz GLS 450 problems

UNKNOWN OR OTHER

Window trim on the passenger rear window fell off while driving- it put others at risk by flying off the vehicle on the interstate- Mercedes Benz of Omaha quoted replacement of the window trim parts- no warning messages on dash

NHTSA complaint #11738164 — an unverified report by a vehicle owner.

STRUCTURE:BODY

Window trim on the passenger rear window fell off while driving- it put others at risk by flying off the vehicle on the interstate- Mercedes Benz of Omaha quoted replacement of the window trim parts- no warning messages on dash

NHTSA complaint #11738164 — an unverified report by a vehicle owner.

STRUCTURE

The contact owns a 2020 Mercedes Benz GLS. The contact stated that while driving on the highway, the rear door window trim bars on the passenger side detached from the window. The vehicle was taken to the dealer where they diagnosed as a rear door window trim detachment however the vehicle was not repaired. The manufacturer was not notified of the issue. The approximate failure mileage 65,000.

NHTSA complaint #11738177 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: WARNINGS

On a sunny afternoon without zero clouds in the sky, 75 degrees I was driving at 35 mph on a two-lane road with no cars in front of me, behind me, or coming in the other direction, the brakes were urgently and automatically applied and the seat belts dramatically tightened. The system showed a large red X on the screen. It was obvious the automated safety system mistakenly thought we were about to crash into something but there wasn't anything but smooth asphalt.

NHTSA complaint #11726166 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

The vehicle (2020 GLS 450) suffers from terminal infrastructure "Electronic Rot," resulting in a consistent Breach of FMVSS 111 (Rearview Visibility) and dangerous Automatic Emergency Braking hallucinations. On 03/08/2026, a routine car wash triggered multiple system failures, including "Camera View Restricted" and "Adaptive Highbeam Assist Currently Unavailable," proving the electrical architecture is compromised by minor moisture. This is a multi-dealer failure: the vehicle was sold as "Certified Pre-Owned" by Mercedes-Benz of Fredericksburg with undisclosed active "Special Procurement" status; a 200-day attempted EIS remediation at i.g. Burton failed to resolve the hazards; and the regular service center, Mercedes-Benz of Annapolis, has failed to remediate the ongoing "Electronic Rot." All parties are currently withholding machine-level XENTRY diagnostic sequences required to verify the vehicle's safety status.

NHTSA complaint #11723015 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: WARNINGS

The vehicle (2020 GLS 450) suffers from terminal infrastructure "Electronic Rot," resulting in a consistent Breach of FMVSS 111 (Rearview Visibility) and dangerous Automatic Emergency Braking hallucinations. On 03/08/2026, a routine car wash triggered multiple system failures, including "Camera View Restricted" and "Adaptive Highbeam Assist Currently Unavailable," proving the electrical architecture is compromised by minor moisture. This is a multi-dealer failure: the vehicle was sold as "Certified Pre-Owned" by Mercedes-Benz of Fredericksburg with undisclosed active "Special Procurement" status; a 200-day attempted EIS remediation at i.g. Burton failed to resolve the hazards; and the regular service center, Mercedes-Benz of Annapolis, has failed to remediate the ongoing "Electronic Rot." All parties are currently withholding machine-level XENTRY diagnostic sequences required to verify the vehicle's safety status.

NHTSA complaint #11723015 — an unverified report by a vehicle owner.

BACK OVER PREVENTION: SENSING SYSTEM: CAMERA

The vehicle (2020 GLS 450) suffers from terminal infrastructure "Electronic Rot," resulting in a consistent Breach of FMVSS 111 (Rearview Visibility) and dangerous Automatic Emergency Braking hallucinations. On 03/08/2026, a routine car wash triggered multiple system failures, including "Camera View Restricted" and "Adaptive Highbeam Assist Currently Unavailable," proving the electrical architecture is compromised by minor moisture. This is a multi-dealer failure: the vehicle was sold as "Certified Pre-Owned" by Mercedes-Benz of Fredericksburg with undisclosed active "Special Procurement" status; a 200-day attempted EIS remediation at i.g. Burton failed to resolve the hazards; and the regular service center, Mercedes-Benz of Annapolis, has failed to remediate the ongoing "Electronic Rot." All parties are currently withholding machine-level XENTRY diagnostic sequences required to verify the vehicle's safety status.

NHTSA complaint #11723015 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

The vehicle is experiencing deterioration of the main engine wiring harness insulation, resulting in exposed wires contacting each other. This condition has caused intermittent check engine lights and electrical fault codes. The dealership has confirmed that the wiring insulation has degraded, allowing wires to contact each other. The issue appears related to material durability of the harness rather than external damage. The concern is that continued deterioration could result in: •Sudden engine misfire •Loss of power while driving •Engine stalling •Potential electrical short circuit An unexpected loss of engine power at highway speeds could increase the risk of a crash. The dealership indicated that similar harness insulation concerns have been observed on other M256-equipped vehicles. This appears to be a potential safety-related defect involving engine wiring insulation durability.

NHTSA complaint #11719907 — an unverified report by a vehicle owner.

ENGINE

The vehicle is experiencing deterioration of the main engine wiring harness insulation, resulting in exposed wires contacting each other. This condition has caused intermittent check engine lights and electrical fault codes. The dealership has confirmed that the wiring insulation has degraded, allowing wires to contact each other. The issue appears related to material durability of the harness rather than external damage. The concern is that continued deterioration could result in: •Sudden engine misfire •Loss of power while driving •Engine stalling •Potential electrical short circuit An unexpected loss of engine power at highway speeds could increase the risk of a crash. The dealership indicated that similar harness insulation concerns have been observed on other M256-equipped vehicles. This appears to be a potential safety-related defect involving engine wiring insulation durability.

NHTSA complaint #11719907 — an unverified report by a vehicle owner.

UNKNOWN OR OTHER

The sunroof spontaneously shattered while driving down the interstate. No other cars involved and no rocks or debris caused it. It was inspected and repaired at a Mercedes dealer, however, Mercedes refused to cover the repair under the pre-owned certified warranty. We had to file an insurance claim. In doing research, it appears this is a common and ongoing problem with various models of Mercedes.

NHTSA complaint #11658502 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

The vehicle, 2020 Mercedes-Benz GLS450, was being backed out of the garage when an electrical failure occurred causing the vehicle to malfunction. This was a major safety issue that caused the entire vehicle electrical control systems to fail as the vehicle would not turn-off. The vehicle eventually turned-off and was not operational. It was towed to a local dealer where we were they discovered that a heating/cooling system hose caused moisture to enter the cab of the vehicle. The end result was major electrical damage to the vehicle control system of the vehicle. This vehicle is my wife's primary means of travel along with our 4 young children. Had this major malfunction occurred while on a highway going at high speeds a parish the thought of what could have happened to the safety of my wife and children. Per attached dealership bill, the dealership was not able to obtain coverage for this $4,255.15 repair bill. In addition, I did find other Mercedes-Benz GLS450 models who were recalled for this very safety issue where moisture in the cab resulted in major electrical control systems of the vehicle.

NHTSA complaint #11657650 — an unverified report by a vehicle owner.

POWER TRAIN

On numerous occasions the transmission does not fully down shift to the next lower gear and then when I have to accelerate quickly it will drop down to the lower gear like it’s supposed to but won’t shift out to the next higher gear and when I let my foot off the accelerator the truck slows down quickly like applying the brakes which almost had me rear ended a few times and now the adaptive cruise control is malfunctioning

NHTSA complaint #11653819 — an unverified report by a vehicle owner.

ELECTRICAL SYSTEM

I am writing to escalate an unresolved service issue with my 2020 Mercedes Benz GLS 450, VIN [XXX] . During a maintenance service on March 6, my trusted independent services shop for 25 years, Carrera Motors in San Mateo CA, identified that the electrical harness of my GLS 450 was significantly damaged. The plastic casing around the wires had effectively disintegrated, exposing the wires directly to the engine. Carrera Motors indicated that this was a serious issue and does not normally occur with a 5 year old vehicle. They encouraged me to contact Mercedes directly. At the instruction of Carrera Motors, I contacted Mercedes customer care on March 10 and was issued a case number (#[XXX]) for the harness issue. She mentioned that someone would get back to me within 3 business days. Unfortunately, 3 days went by without a response. I called and left 3 messages over the next 2 days. Finally, MBUSA returned my call and instructed me to take the car to an authorized Mercedes dealer. At my own expense, I had the car towed from Carrera Motors to Autobahn Motors in Belmont CA on March 18. Mark Nissen at Autobahn was responsible for the service of my vehicle. He and his services team have verified that the electrical harness was seriously damaged and needs to be replaced at a cost of $5,009.99. Replacement is considered critical, and it’s been identified as a serious safety issue. This issue has not been resolved. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11652008 — an unverified report by a vehicle owner.

ENGINE

I am writing to escalate an unresolved service issue with my 2020 Mercedes Benz GLS 450, VIN [XXX] . During a maintenance service on March 6, my trusted independent services shop for 25 years, Carrera Motors in San Mateo CA, identified that the electrical harness of my GLS 450 was significantly damaged. The plastic casing around the wires had effectively disintegrated, exposing the wires directly to the engine. Carrera Motors indicated that this was a serious issue and does not normally occur with a 5 year old vehicle. They encouraged me to contact Mercedes directly. At the instruction of Carrera Motors, I contacted Mercedes customer care on March 10 and was issued a case number (#[XXX]) for the harness issue. She mentioned that someone would get back to me within 3 business days. Unfortunately, 3 days went by without a response. I called and left 3 messages over the next 2 days. Finally, MBUSA returned my call and instructed me to take the car to an authorized Mercedes dealer. At my own expense, I had the car towed from Carrera Motors to Autobahn Motors in Belmont CA on March 18. Mark Nissen at Autobahn was responsible for the service of my vehicle. He and his services team have verified that the electrical harness was seriously damaged and needs to be replaced at a cost of $5,009.99. Replacement is considered critical, and it’s been identified as a serious safety issue. This issue has not been resolved. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11652008 — an unverified report by a vehicle owner.

ENGINE

On a long road trip - about halfway on [XXX] - received an error message on 48v system malfunction - immediately called nearest Mercedes dealership (Richmond Va) to schedule a service - while on the line received an engine overheating pull over and shut it off message - at this point vehicle deaccelerated over riding my control of vehicle speed. Had to navigate from far left lane to right hand emergency lane at 40 mph - very dangerous maneuver as losing power. Vehicle was towed and received a 48v software update - software that deaccelerates the vehicle with no override for safety is a real problem INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11639933 — an unverified report by a vehicle owner.

SUSPENSION

The shock absorbers have prematurely failed as other recalled 2020 GLS vehicles, but our VIN is not showing under the recall campaign 20V329000. Can our vehicle be included on this recall?

NHTSA complaint #11637274 — an unverified report by a vehicle owner.

VISIBILITY/WIPER

intermittent rear view camera inoperable when you shift from park to reverse. Doesnt come on even if you turn off and tune on the engine.

NHTSA complaint #11615337 — an unverified report by a vehicle owner.

VEHICLE SPEED CONTROL

The adaptive cruise control feature of this vehicle on various highways [XXX] , [XXX] and the [XXX] ) and in various locations while traveling at highway speeds has mis-read speed limit signs and aggressively decelerated(I assume by using its regenerative braking) to as low as 35mph while traffic is moving at 65+mph. The dealership was unable to duplicate this issue. No faults are displayed to the driver. I do not know if rear brake lights are illuminated when this occurs. This is an aggressive and scary deceleration with no warning. I fear a rear end collision is likely. No one aside from the dealership has inspected this vehicle INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11614077 — an unverified report by a vehicle owner.

FORWARD COLLISION AVOIDANCE: ADAPTIVE CRUISE CONTROL

The adaptive cruise control feature of this vehicle on various highways [XXX] , [XXX] and the [XXX] ) and in various locations while traveling at highway speeds has mis-read speed limit signs and aggressively decelerated(I assume by using its regenerative braking) to as low as 35mph while traffic is moving at 65+mph. The dealership was unable to duplicate this issue. No faults are displayed to the driver. I do not know if rear brake lights are illuminated when this occurs. This is an aggressive and scary deceleration with no warning. I fear a rear end collision is likely. No one aside from the dealership has inspected this vehicle INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA complaint #11614077 — an unverified report by a vehicle owner.