2024 Mercedes-Benz GLS Problems: 7 Known Issues

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 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 2020-2025 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 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 2020-2025 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 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.