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 Find Your Problem Now → 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.

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Frequently Asked Questions

What is the most common problem with the Mercedes GL / GLS?

The most frequently reported issue on the Mercedes GL / GLS is AIRMATIC Air Suspension Failure. 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.

How many Mercedes GL / GLSs are on UK roads?

There are an estimated 18,000+ Mercedes GL / GLSs currently on UK roads.

What tyres does the Mercedes GL / GLS use?

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.

Will a warning light fail my Mercedes GL / GLS's MOT?

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.

Similar Issues on Other Models

Kia Sorento — third row seat mechanism shows up here too Land Rover Discovery — also commonly develops DPF blockage

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 →