On this engine the injectors were also listed as parts to be replaced in the maker's own programme, which means their failure is a known one. A faulty injector puts too much fuel into the cylinder. The liquid cannot be compressed, so the piston hits it on its way up: this is hydraulic lock, and it can damage the connecting rod bearing and the connecting rod as well. The early sign is rough running and hard starting. The fault can start from 60,000 km. The maker ran a separate programme for this engine, called the Customer Care Package, from December 2014. The franchised dealers had to check seven parts: the timing chain, the fuel injectors, the mass air flow sensor, the crankcase vent lines, the battery, the vacuum pump and the low pressure fuel sensor. These had to be replaced free of charge, even if the car had already fallen out of the four-year, 50,000-mile warranty. The same programme also shortened the oil change interval: 10,000 miles or one year instead of 15,000 miles or two years. Before buying it is therefore worth asking whether this programme was carried out on the car.

The timing chain stretches between 80,000 and 120,000 km, and the plastic chain guides break. The broken pieces end up in the sump and block the lubrication system. From then on the engine is starved of oil, which takes the bearings and the turbochargers with it. The early sign is a metallic rattling from the front of the engine on a cold start. The stretching of the chain also features in the American class actions, alongside the extreme oil consumption. The maker ran a separate programme for this engine, called the Customer Care Package, from December 2014. The franchised dealers had to check seven parts: the timing chain, the fuel injectors, the mass air flow sensor, the crankcase vent lines, the battery, the vacuum pump and the low pressure fuel sensor. These had to be replaced free of charge, even if the car had already fallen out of the four-year, 50,000-mile warranty. The same programme also shortened the oil change interval: 10,000 miles or one year instead of 15,000 miles or two years. Before buying it is therefore worth asking whether this programme was carried out on the car.

The heart of the four wheel drive in the longitudinal engine BMW X models (X3, X5 and the X1 E84) is the ATC transfer case. It has two faults, and you can feel both while driving.

The valve stem seals start to lose their sealing from 90,000 km, and oil gets into the combustion chamber along the valve stem. The burning oil lays soot on the piston rings, they start to stick, and from then on the consumption grows further; the lubrication also gets tighter and the exhaust smokes. The scale of the consumption on this engine is extraordinary. In the American class action the plaintiffs report around one litre every 1,200 km, and one of them one litre every 1,600 km. In 2013 the maker issued a new oil consumption standard for this engine in a bulletin, and took the position that this is not a defect: according to it every one of its engines may use that much. The lawsuit points out that with this standard the owner has to top up the oil twenty times before reaching the factory 15,000-mile oil change interval. The maker ran a separate programme for this engine, called the Customer Care Package, from December 2014. The franchised dealers had to check seven parts: the timing chain, the fuel injectors, the mass air flow sensor, the crankcase vent lines, the battery, the vacuum pump and the low pressure fuel sensor. These had to be replaced free of charge, even if the car had already fallen out of the four-year, 50,000-mile warranty. The same programme also shortened the oil change interval: 10,000 miles or one year instead of 15,000 miles or two years. Before buying it is therefore worth asking whether this programme was carried out on the car. The repair means opening the cylinder head, and because of the V layout of the engine on both sides.

The ZF eight speed automatic (BMW Steptronic 8HP family) has two faults, and you can feel both.