Mercedes Sprinter Common Faults (W906 & W907): What Every Owner and Fleet Manager Should Know
The Sprinter is the backbone of countless London businesses — but four well-known faults can put one off the road for days. Here is what they are and how to prevent them.
The Sprinter: built for work, but not indestructible
The Sprinter W906 (2006–2018) and W907 (2018–present) are the default choice for London commercial operators for good reason — they are durable, practical, and supported by a large independent specialist network. However, the demands of commercial use — high mileage, heavy loads, urban stop-start driving — accelerate wear on specific components that every owner and fleet manager should budget for.
2. OM651 injector seal failure
The copper injector seals on OM651 diesel engines can fail, causing a "chuffing" noise and black carbon deposits around the injector base. This is particularly common on high-mileage Sprinters because they operate under sustained load, which increases combustion pressure and accelerates seal wear. If ignored, the leaking combustion gases carbonise the injector into the head, making removal difficult and sometimes requiring head removal. Replacement of the seals as preventative maintenance every 100,000 miles costs £200–£400. Waiting until they fail can turn a £400 job into a £1,500+ job.
3. Dual-mass flywheel failure
The dual-mass flywheel (DMF) absorbs vibration from the diesel engine. On Sprinters used for urban delivery work — constant stop-start, frequent clutch operation — the DMF can wear prematurely, causing a rattling noise at idle that disappears when the clutch is depressed. Replacement involves removing the gearbox and costs £800–£1,200. Fitting a single-mass flywheel conversion is an option for some operators, eliminating future DMF failure, at the cost of increased gearbox noise and vibration.
4. AdBlue heater and NOx sensor failure
Same as the passenger-car Mercedes diesels: the AdBlue tank heater and NOx sensors fail on Euro 6 Sprinters. For a commercial operator, the "starts not possible" countdown is particularly damaging because it can strand a loaded van. AdBlue tank replacement: £900–£1,300. Prevention is limited, but using ISO 22241 certified AdBlue and having the system checked at each service reduces the risk of unexpected failure.
5. Rear axle bearing and glow plug module
Sprinters operating at or near their maximum gross vehicle weight experience accelerated rear axle bearing wear. A humming noise from the rear that increases with road speed is the warning sign. Replacement: £400–£700 per side. The glow plug module also fails with age on OM651 engines, causing hard cold starting. Replacement: £150–£250. For fleet operators, we recommend scheduling these checks at every 50,000-mile interval to catch wear before it causes a breakdown.