2020 Mercedes-Benz GLS Problems: 18 Known Issues

On the 2020-2023 Mercedes-Benz GLS, on 48V mild-hybrid GLS 450, GLS 580, Maybach GLS 600 and AMG GLS 63 models, the ground cable bolt for the 48V system located under the front passenger seat may not have been tightened to specification at the factory. A loose ground lug increases electrical resistance which, combined with the very high currents the 48V starter-alternator (ISG) draws, can cause the connection to overheat, melt surrounding components and, in the worst case, start a fire. This prompted a U.S. safety recall (NHTSA 24V207) covering roughly 116,020 GLE and GLS vehicles built between June 2017 and January 2023. This is a physical hardware/connection defect distinct from a discharged 48V battery — the connection itself overheats.

On the 2020-2025 Mercedes-Benz GLS, the 48V EQ Boost mild hybrid system causes excessive battery drain when parked. A software bug in the 48V battery management module fails to properly enter sleep mode, draining both the 48V lithium-ion and 12V lead-acid batteries.

On the 2020-2021 Mercedes-Benz GLS, two software defects on early X167 GLS leave the driver without a backup-camera image, a FMVSS 111 violation. Under 21V-354 (May 2021), the MBUX communication-module software on 2020-2021 GLS 450, GLS 580, Maybach GLS 600 and AMG GLS 63 could leave the MBUX display black after startup or make it reboot about 50 seconds after startup, so the rearview camera image might not be displayed. Under 22V-232 (April 2022) the rearview camera's own firmware on 2020 GLS 450 (about 126,000 Mercedes vehicles in total) could fail to render the image; the supplier fixed production from May 26, 2021. 22V-232 is distinct from general MBUX freezing: that failure is in the rearview camera's own software.

On the 2020-2025 Mercedes-Benz GLS, gLS X167 owners report the MBUX infotainment system freezing, showing a black or flickering screen, distorted display, unresponsive touch controls, or randomly rebooting. The faults are intermittent and often software-related, frequently triggered by or persisting through OTA/software updates. While usually not safety-critical, a frozen unit can disable navigation, climate controls and the central display, which is a notable annoyance in a vehicle at this price point.

On the 2017-2023 Mercedes-Benz GLS, the GLS AIRMATIC system is prone to air spring leaks and compressor failure due to the vehicle's heavy curb weight (roughly 5,300-5,800 lbs). Front air springs tend to fail first. The compressor overworks to maintain ride height and eventually burns out.

On the 2020 Mercedes-Benz GLS, separate from the well-known AIRMATIC air-spring bellows failures, a batch of 2020 GLE 450, GLS 450 and GLS 580 left the factory with front strut and rear shock absorber piston assemblies whose seals did not meet specification. The dampers leak hydraulic fluid and lose damping early, which shows up as a bouncy, floaty ride, oil film on the strut body and degraded handling on a vehicle that already weighs 5,500 lb. Mercedes covered the affected build range (38 vehicles produced April-September 2019) under NHTSA safety recall 20V-329 (MBUSA 2020090001); the go-parts guide and owner threads show the same early-damper-leak symptom persisting on later X167 examples.

On the 2020-2023 Mercedes-Benz GLS M256 3.0L I6 turbo + 48V EQ Boost, recall 24V118 covers model-year 2020-2023 GLS 450 vehicles equipped with the six-cylinder gasoline engine and nine-speed transmission. If a 7th-to-6th downshift is not completed during slight braking while other conditions coincide, including low transmission-oil temperature and 48V recuperation, the engine can stall and propulsion can be lost. Steering and braking remain functional, and the engine can be restarted after the vehicle stops. The 105,071 total is the combined GLE 450 and GLS 450 recall population, not owner reports.

On the 2017-2023 Mercedes-Benz GLS, the 9G-Tronic nine-speed automatic exhibits harsh low-speed shifts and hunting between gears on inclines. The transmission software struggles to select the optimal gear among nine ratios, particularly noticeable in stop-and-go traffic.

On the 2020 Mercedes-Benz GLS, mercedes determined that on 2016-2020 gasoline vehicles built on multiple platforms - including MY2020 GLS 450 and GLS 580 on the X167 platform - the fuel rail and injectors may not have been cleaned properly before assembly. Trapped particles can damage the seal between the high-pressure fuel rail and the injector, and over the life of the vehicle that seal can begin to weep fuel into the engine compartment, where it may reach hot exhaust components. The Part 573 report lists a fuel odor or a check-engine light from fuel-rail-pressure deviation as the only warnings.

On the 2020-2025 Mercedes-Benz GLS OM656 3.0L I6 diesel, the OM656 diesel uses a precise Bosch CP4 common-rail high-pressure fuel pump that reacts poorly to low-quality diesel or fuel contamination. Even minor tank impurities or a single mis-fueling event can damage the pump and injection nozzles, and metallic debris from a failing CP4 can circulate through the fuel system. Clogged fuel filters from contaminated fuel further disrupt combustion and cause power loss. Repairs can be extensive because a failed CP4 may require cleaning or replacing injectors, lines and the high-pressure pump. This is an EU-relevant concern given diesel availability and variable fuel quality across markets.

On the 2020-2025 Mercedes-Benz GLS, the 4MATIC transfer case on the GLS is prone to internal bearing wear, typically beginning with fluid degradation or a slow leak from the output/case seals. As the bearings wear, owners report a whining or grinding noise that increases with vehicle speed and worsens over time. On the X167 generation the transfer case is more closely integrated with the 9G-Tronic transmission, so a severe bearing failure can shed metal debris into the transmission, turning a contained repair into a much larger and more expensive one. In the worst case a complete failure can lock the drivetrain or cause sudden loss of drive. Running mismatched/uneven tires accelerates the wear.

On the 2020-2025 Mercedes-Benz GLS, the large panoramic sunroof on the X167 GLS develops water leaks at the drain tubes or seal interface. Water enters the headliner and can drip into the cabin, staining the headliner and potentially damaging the overhead electronics.

On the 2020-2024 Mercedes-Benz GLS M256 3.0L I6 turbo, owners of GLS 450 models with the M256 3.0L turbocharged inline-six report elevated oil consumption that tends to surface at higher mileage (commonly reported around 60,000 miles / ~100,000 km). The pattern — oil disappearing without visible external leaks — points to internal piston ring / cylinder wear as the likely cause, and in some documented cases correcting it required significant engine disassembly. There is no factory recall specifically for piston rings/oil consumption on the M256 as of 2026, so repairs typically fall on the owner once out of warranty.

On the 2020-2021 Mercedes-Benz GLS, on 2020-2021 X167 GLS (GLS 450, GLS 580, Maybach GLS 600, AMG GLS 63) the evaporator drain hoses were not always seated to specification at the Tuscaloosa plant, so A/C condensate drains into the passenger compartment instead of under the car. Owners see soaked front carpets and fogged windows. The Part 573 report for 23V-177 warns that the water pools around control units in the footwells and can cause corrosion or short circuits, with consequences that include the eCall system being unavailable, the vehicle refusing to unlock or start, engine limp-home mode activating while driving, and an increased fire risk. Mercedes recalled the issue three times - 19V-587 (2020 build), 21V-288 (2020-2021) and the 2023 expansion 23V-177 - and only claimed a production fix after February 3, 2021.

On the 2020-2025 Mercedes-Benz GLS OM656 3.0L I6 diesel, eU-market GLS 350d/400d models with the OM656 3.0L inline-six diesel suffer from sensitivity in the exhaust aftertreatment chain. The EGR (AGR) valve, diesel particulate filter (DPF) and SCR/AdBlue system are sensitive to poor fuel quality, short-trip driving and temperature swings. Clogged DPF, a dirty/sticking EGR valve, or a faulty EGR differential-pressure sensor cause power loss, failed regenerations, dashboard warnings and limp-home mode. A German motor-talk owner thread on the GLS X167 400d documents poor acceleration that resolves after a restart, traced to a replaced EGR differential-pressure sensor under warranty. This primarily affects diesels not sold in the US, so it is especially relevant to the EU market.

On the 2020-2023 Mercedes-Benz GLS, on 2020-2022 GLE and GLS built at MBUSI Tuscaloosa, the chrome/black trim bars on the rear door windows were not fastened to specification during assembly. Under wind load at speed the bar can separate from the door and become a road hazard for following traffic. The initial September 2022 recall (22V-680) covered about 161,000 GLE/GLS including 2020-2022 GLS 450, 2020-2021 GLS 580, 2021 Maybach GLS 600 and 2021 AMG GLS 63; Mercedes then added roughly 70,000 more 2022-2023 vehicles under 23V-178. Mercedes claimed a production fix from April 25, 2022, but the second recall shows later builds were still affected. Owners on MBWorld also report the matching tailgate spoiler and tow-hook covers letting go, pointing to the same adhesion/fastening quality problem on this generation's exterior trim.

On the 2020-2022 Mercedes-Benz GLS, a supplier production deviation meant the spring inside the left and right third-row seatback locking mechanism on 2020-2022 X167 GLS (GLS 450, GLS 580 and 2021 AMG GLS 63; about 59,574 vehicles) may not have been installed. Without the spring the latch does not hold the seatback as designed, so in a rear or frontal collision the third-row seatback can fold and fail to restrain the occupant or cargo. There is no warning to the driver; the seatback still appears to latch in normal use.

On the 2020-2023 Mercedes-Benz GLS, on 2020-2023 X167 GLS models with MB-Tex synthetic upholstery the driver and passenger front seat covers split open along the side bolster and thigh-support seams, often within the first two to three years and well under 40,000 miles. MBWorld owners report the driver seat going first, then the passenger seat, and Mercedes acknowledging the original material by issuing revised seat-cover part numbers (driver A16791097148U01, passenger A16791088148U01, replacing 167-910-86-05-8U01 / 167-910-09-00-8U01). Dealers have covered replacement under warranty or goodwill, but some owners waited more than a year for the passenger-side revised cover and others were refused as 'wear and tear'.