Quick Facts — Mercedes GL / GLS

Est. On UK Roads
18,000+
Years Made
2006–present
Common Engines
3.0 V6 diesel (GL350d), 4.5 V8 (GL450), 5.5 V8 (GL500/GLS500), 3.0 inline-6 (GLS400d/GLS450), AMG GLS63

6 Most Common Mercedes GL / GLS Problems

These are the faults most frequently seen on the Mercedes GL / GLS by UK garages — ranked by how commonly they occur and what they cost to fix.

1
AIRMATIC Air Suspension Failure
High Priority
AIRMATIC air suspension is standard on all GL/GLS models and is the most commonly reported fault — compressor failure and strut leaks cause the car to sit on its bump stops.
💷 Typical repair cost: £600–£4,000
2
DPF Blockage (CDI Diesel)
High Priority
Diesel GL/GLS models on short journeys develop DPF blockages — a large 7-seat diesel SUV on a school run is a very high DPF risk.
💷 Typical repair cost: £200–£2,000
3
AdBlue System (GLS Diesel)
High Priority
GLS diesel models require AdBlue. Running dry or injector faults cause warnings and prevent restarting.
💷 Typical repair cost: £10–£1,000
4
Transfer Box Wear (4MATIC)
Watch
The 4MATIC transfer box requires regular fluid changes. Neglect leads to vibration and AWD failure.
💷 Typical repair cost: £500–£3,000
5
9G-Tronic / 7G-Tronic Gearbox Issues
Watch
Both gearbox generations can develop judder and valve body faults when servicing is neglected.
💷 Typical repair cost: £500–£4,500
6
Third Row Seat Mechanism
Low Priority
The electric third row seat folding mechanism can develop motor and sensor faults on older GL models.
💷 Typical repair cost: £200–£600

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Mercedes GL / GLS — MOT Tips

AIRMATIC suspension must hold correct ride height for MOT — failing compressors are the most common issue. DPF and AdBlue warnings are MOT-relevant or automatic fails on diesel models. AWD and gearbox warning lights must be clear. All 7 seatbelts must be functional on 7-seat examples.

Engine management light on before your MOT? It's an automatic fail. Run a MotorLoom diagnostic for £1.99 to get the likely cause and repair cost before booking the test.

Mercedes GL / GLS Tyres

Most Mercedes GL / GLS models run 275/50 R19 or 275/45 R20 or 285/40 R21 depending on trim level and year. Always check the placard inside the driver's door for the exact size for your vehicle.

Summary

The GL and GLS are outstanding used large 7-seat SUVs. AIRMATIC service history is the non-negotiable check. The GLS400d with full service history is the most reliable diesel choice. Budget for higher servicing costs than average and use a specialist Mercedes independent rather than main dealer. The GL350d BlueTEC is the best value entry point.

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Other Mercedes-Benz Models

Mercedes C-Class → Mercedes E-Class → Mercedes A-Class → Mercedes GLC →