Mercedes-Benz M-Class W164 ML 420 CDI
Model overview
A spacious, comfortable luxury SUV. Ageing suspension, electrical equipment and four-wheel-drive components can make upkeep expensive.
Pros
- Comfortable spacious cabin
- Useful 4MATIC traction
- Good towing capability in suitable specifications
Cons
- High running costs
- Costly driveline repairs
- AIRMATIC adds cost where fitted
Common problems & ownership concerns
Potential impact: Low · Medium · High. This describes possible consequences, not fault likelihood.
- Transfer-case wearMedium
- AIRMATIC faults where fittedMedium
- Electrical equipment faultsMedium
- Suspension wear and corrosionMedium
Maintenance
Maintain the gearbox, transfer case, differentials and fitted suspension under their specified schedules.
Engine overview · 4.0L 8-cyl DIESEL
A powerful and refined V8 diesel for the ML 420 CDI, but its twin-turbo, injection, intake and emissions systems make condition and documented servicing important.
Pros
- Strong performance and towing ability
- Refined V8 diesel character
- Well suited to long-distance driving
Cons
- Complex and potentially expensive repairs
- High fuel and maintenance demands
- Specialist diagnosis may be needed
Common problems & ownership concerns
Potential impact: Low · Medium · High. This describes possible consequences, not fault likelihood.
- Intake swirl flaps and actuatorMedium
- Turbocharger control and boost systemHigh
- Diesel injectors and sealingHigh
- DPF and EGR emissions systemMedium
Maintenance
Follow the VIN-specific Mercedes-Benz oil specification and service schedule, with documented attention to diesel injection, turbocharging and emissions equipment.
These are general ownership concerns, not a diagnosis. Equipment and engine details vary by version and production date.
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