What 38 owners told NHTSA about the 2020 Mercedes-benz GLS

AMENDMENT TO ACTIVE CASE 11723015. CRITICAL AIRBAG & SAFETY DEFECTS. This files a safety defect amendment to open case 11723015. Diagnostic scans confirm central data bus network collapse on VIN [XXX] has migrated into safety-critical occupant restraint and visibility modules, violating 49 U.S.C. § 30118. I. AIRBAG & RESTRAINT HAZARDS Scans from [XXX], document active faults: DTC U042782: "Implausible data received from Electronic Ignition Lock." The SRS module receives corrupted data from the failed ignition gateway, creating risk of airbag non-deployment. DTC B007A13: Passenger seatbelt pre-tensioner open circuit; occupants are unprotected against crash displacement. DTC B11FA4B: Active "Overtemperature" faults in heating elements indicate localized thermal short-circuit risk. II. HARDWARE DECAY Physical teardown confirmed structural oxidation on the central gateway motherboard and corroded connector pins. Modular swaps failed; network lock code U016887 returned within 8 months. Raw dealer records are available for federal inspection. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11741714

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 ODI 11738164

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 ODI 11738177

The engine wiring harness insulation near the ignition coil connectors prematurely deteriorated due to prolonged exposure to engine heat in the turbocharger/exhaust area. Multiple wiring connectors exhibited brittle, cracked insulation with exposed conductors. The degraded wiring began shorting within the ignition system, causing engine misfires, ignition circuit faults, and eventual loss of engine operation. While being operated by a rental customer the vehicle developed severe misfires followed by electrical shorting, smoke, localized flames in the engine harness area, and eventual engine shutdown. The flames self-extinguished after the electrical shorting stopped, but portions of the harness insulation showed thermal damage and overheating. The customer became stranded due to the vehicle becoming inoperable. Diagnostic faults included ignition coil circuit open faults and ignition primary circuit faults. The vehicle ultimately became inoperable due to the electrical failure. Inspection revealed multiple adjacent ignition harness connectors showing progressive heat-related insulation degradation in the same high-temperature area, indicating a broader harness material failure rather than isolated damage. This failure occurred on a 5-year-old vehicle. Engine wiring harness insulation should not prematurely degrade and short under normal operating conditions.

NHTSA ODI 11736819

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 ODI 11726166

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 ODI 11723015

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 ODI 11719907

The fuel rail system failed on the passenger side of the engine and leaks. This is the same issue seen on, but VIN number isn't apart of it: Campaign No. : 2022030003 CA DMV. : 220303 NHTSA ID 21V961 I have taken the vehicle to a Mercedes dealer twice for the concern of smelling gas. The second time I had a video but the service tech couldn't replicate the leak. This safety concern pose a great risk as the gas could come into contact with a hot surface and ignite but passenger at HIGH risk. The problem has taken to the dealer twice with video showing the leak., however they cannot reproduced confirmed/replicate it. No the vehicle or component has not been inspected by the police, insurance representatives or others? But has been taken to the dealership, not the manufacturer. No warning lamps, messages or other symptoms of the problem prior to the failure, and when did they first appear?Just when it leaks there is a strong gas smell as well as a visual of where the leak is coming from.

NHTSA ODI 11705195

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 ODI 11658502

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 ODI 11657650

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 ODI 11653819

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 ODI 11652008

The suspension has failed despite changing engine mounts. It is available for inspection if needed. I also believe there is Premature wear of the front struts and rear shock absorbers. This can affect vehicle handling and control, increasing the risk of a crash. There were no warning lamps and it has been inspected by various mechanics including Mercedes

NHTSA ODI 11652075

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 ODI 11639933

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 ODI 11637274

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 ODI 11615337

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 ODI 11614077

We intermittently experience phantom braking, including on the highway with no objects or vehicles ahead of us (for example, not on a curve, no vehicle visible within half a kilometer). Vehicle abruptly slows. This includes when in a lane (no lane change). It also can occur during a properly indicated lane change. It occurs when we are driving the posted limit. It also occurs when there are no parallel nearby roads. This appears to be a significant safety issue.

NHTSA ODI 11609189

I have received multiple notifications over several months that read "Camera view restricted". This impacts the collision avoidance and adaptive highbeam assist functions. Dealer has offered no service recommendations.

NHTSA ODI 11600969

While driving on the New Jersey Turnpike on November 17, 2023, a burning smell was noticed inside the car. The smell lasted about an hour. No smoke was present and the car continued to operate. While concerned, I assumed it was environmental and outside the car. On November 25, 2023 my car threw a 48V battery warning and forcibly shut off. We were not on a highway at the time and were able to pull over to a gas station. MB roadside was called and towed the car to Euro Motorcars Devon of Devon, PA, the local Mercedes-Benz dealer and where I purchased the car and receive service. Over the course of the next few weeks the service department concluded and ultimately determined that there were burnt out cables which were connected to the 48V battery (this is highlighted in the service receipt attached). This repair was not covered under my warranty and lead to a $5,804.56 repair bill. The car was repaired to my satisfaction and the bill was paid in full on December 14, 2023 determined the matter was complete. On or about May 1, I received a recall notice from MBUSA. The ID is 2024040002 and the NHTSA Recall ID is 24V207. This recall specifically called out the 48V battery connections and potential for misconnections to cause fire. This is the exact issue that is clearly articulated in the service report (attached). After six weeks attempting full reimbursement, MB considered the issue closed and their official position was that I was only entitled to $337.08 for the actual recall of the battery connection check. Of course the connections would now be correct as they fixed them and replaced the cables that caught fire. I am escalating this to your department and seek full reimbursement from Mercedes for this repair performed. This failure occurred prior to the recall notice and is the singular event that the recall is to mitigate that happened.

NHTSA ODI 11600435

The passenger rear wheel brake caliper lower bolt got loose. The bolt is most likely not available for inspection. The caliper body then started rubbing against the wheel inside surface and caused a noise. If the caliper body had jammed into the wheel and stopped it from rotating, say on the highway, the vehicle could have skidded or rolled over? The MB dealership inspected and replaced the bolt. There were no warning lamps, messages or other symptoms of the problem prior to the failure. The noise came during braking on tuesday, 28 May. The car was repaired by the MB dealership on Thursday, 30 May.

NHTSA ODI 11591958

Today around 6:47pm. I was reversing my car and I noticed another car in my backup camera and tried shift the gear shift to drive but it didn't work and stayed stuck on reverse and would not moved and the brake pedal and emergency brake wouldn't work.

NHTSA ODI 11587350

The dashboard screen stops working randomly. This is not related to extreme outdoor temp conditions. Mercedes dealer could not reproduce the problem and therefore could not offer any solution. Problem has happened 5-6 times over the past 7 months. Please watch video below: [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11586461

Vehicle would not start. 48v battery light came on. Waited 15 minutes, vehicle started, drove to dealership who did diagnosis. Battery replacement required $1800 + $1200 labor. 2020 vehicle with 61K miles. Bought certified vehicle from MBZ dealership, added a MBZ 3 year or 100K mile extended warranty but this battery is considered a wear and tear item not covered. That would be fine except for the fact that this battery issue is well known to MBZ as it has multiple reported instances of failure on vehicles with 6K to 60K miles.

NHTSA ODI 11561921

I have noticed a significant issue with the AC vent system of my Mercedes GLS 450. The vents seem to be distributing mold smell already took my vehicle multiple times to park place Mercedes in Dallas and they performed service but the issue is persistent. I have taken the vehicle to my local Mercedes service center, where they attempted to address the issue. However, despite their efforts, the problem has persisted. This defect is impacting not only the comfort of my driving experience but also the overall value and performance of the vehicle. We had GLE in my family that had the same issue we took it to Park Place and complained about this many times and end up selling the vehicle as they never resolved the issue. Vehicle: 2017 MERCEDES-BENZ GLE350 VIN: [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11539815