2025 Mercedes-Benz GLS Problems: 2 Issues Every Owner Should Know
2025 model year · 950+ owner reports · Updated April 2026
According to Au7o's analysis of 950+ owner reports, the 2025 Mercedes-Benz GLS has 2 documented known issues. No issues are rated critical, indicating generally reliable ownership. The most commonly reported issue is Panoramic Sunroof Water Leak with 500 owner reports. Across all issues, repair costs range from $100 to $3,500. DIY maintenance guides at au7o.io.
All 2 Known Issues
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.
Common Symptoms
- Water dripping from overhead console area
- Damp headliner after rain or car wash
How to Fix
Clear the sunroof drain tubes with compressed air. Reseal the sunroof glass to the frame if the weatherstrip has shifted. If the headliner is water-stained, it may need cleaning or replacement.
What Owners Are Using
Parts and tips from 500+ owners who fixed this issue
- TipAvoid automated car washes with high-pressure nozzles pointed at the roof. The extreme water pressure overwhelms the sunroof seals and drains. Hand wash or touchless wash only.
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.
Common Symptoms
- Dead battery after sitting for 3-5 days
- Multiple electrical warnings on startup
How to Fix
Update the 48V battery management software at the dealer. If both batteries are deeply discharged, they may need replacement. The 12V battery is $200-400, the 48V battery is $1,500-3,000.
What Owners Are Using
Parts and tips from 450+ owners who fixed this issue
- TipIf the GLS sits for more than a week, connect a battery tender to the 12V battery under the hood. The 48V system draws from the 12V to maintain its state of charge.