The common rail high-pressure pump is lubricated and cooled by the diesel itself, because the pump produces over 2,000 bar and has no separate lubrication circuit. If that lubricating film breaks down, the internal running surface of the pump eats itself and metal debris is produced. The debris travels through the whole system with the diesel, the rail, the injectors and the tank as well, because the return line carries it back and the lift pump draws it in again at every start. From there flushing the injectors does not help, all of them have to be replaced and the tank cleaned too. The failure is reported between 120,000 and 160,000 km, and the repair runs from 1,500 to 15,000 euro depending on how far the debris got. The lubricating film is broken by misfuelling and by long runs with an almost empty tank, because below 5 litres the lift pump also draws air. Plain wear of the pump is a different case: there is no debris and only the pump has to be replaced.

The timing chain of the longitudinal V6 diesel runs at the back of the engine, on the gearbox side, so replacing it means taking out the engine or the gearbox. That alone makes it expensive, but the mechanism is the point: the chains stretch and the hydraulic tensioners lose their pressure. The first and only early sign is a 2 to 3 second metallic rattle audible on a cold start. If that is ignored, the chain jumps or breaks, and the engine is badly damaged inside. The same chain kit also drives the oil pump: if that seizes, the engine is left without lubrication.

The four groups of parts in the air suspension (compressor, valve block, ride height sensors, air springs) work together, and any weak link causes a fault message, an uneven ride height or a car that settles. The characteristic symptom: the car sits down on one corner overnight, levels itself for minutes in the morning, and the compressor runs long and loud. According to the reports the compressor lasts 80,000 to 100,000 km; and a leaking air spring takes the compressor with it, because it keeps trying to make up the loss.