The crankcase breather of the five-cylinder 2.5 TFSI leads the oil vapour into the intake, and the stub of the diverter valve sits directly next to it. When the diverter valve opens on lifting off, it carries the oil vapour along, and the vapour condenses in the air filter housing, because the stub is right in front of the housing. The oil therefore collects on the filter element and in the bottom of the housing, the amount grows with use, and under load oil mist comes out of the intake pipe as well. The consequence is twofold: measurable oil consumption, and oil reaching the intake speeds up the carbon build-up on the intake valves, which is already heavy here because of the direct injection. This is not a broken part but where the line runs, so it shows up around 40,000 km already, and earlier on a car used hard. The repair is rerouting the breather or fitting a catch can, 200 to 600 euro.

While you steer, a grinding, squealing noise comes from the steering column, which many people blame on the power steering pump or the steering rack, although the cause is often the control unit in the steering column, and that is a smaller part, not the rack. Replacing the control unit is the smaller repair, replacing the rack costs much more, and the noise alone does not separate the two, so a fault code read is needed.

The seven speed, wet clutch DQ500 is the DSG of the high torque models (Transporter, Arteon, Tiguan). On a heavy vehicle, on the T5 vans, the splined joint of the differential can shear. Clutch debris blocks the valves of the mechatronics unit, and it jerks on shifts. The pressure sensors fail at around 100,000 to 150,000 km, and then either the even or the odd gears drop out. The control board fails from overheating next to a clogged heat exchanger. It is not repairable, only replaceable.

With direct injection the fuel does not wash the intake valves: the petrol goes into the cylinder, not behind the valve. The oil mist and soot arriving through the EGR and the crankcase ventilation therefore build up on the valve stem and head, and from 80,000 to 100,000 km they restrict the flow. Symptoms are hesitation, loss of power, a rough cold start and misfire. It is not a part failure: it is a consequence of the design, and therefore it comes back. Cleaning (walnut or dry ice blasting) helps for a few tens of thousands of kilometres.

Water gets in through the sunroof drains, the door seals or the window guides, and collects on the floor and in the sill. The water also ruins the wiring and the control units in the floor, which leads to hesitant starting and an alarm going off on its own. With a fault like this, lift the carpet first, because the water is under it.

The G62 sensor tells the engine control unit how hot the coolant is. If it is faulty, the control unit thinks a warm engine is cold, and runs it rich: hard warm or cold starting, a rough idle, markedly increased fuel consumption, and a dash temperature gauge that jumps around or never reaches its usual reading. The part is cheap and can be replaced in half an hour: the trouble is that many people do not recognise it and replace an injector or a lambda sensor instead. If the fault persists, the rich mixture can destroy the catalytic converter too.

Over bumps a booming, squeaking noise comes from the front, and a common cause is a bump stop put back wrongly after a damper replacement: that is not a factory fault, but the result of earlier work. On cars built between 2013 and 2016 the rubber bushes wear out too, the dampers weaken as well, the car rides more harshly, and the tyres wear unevenly. The two faults sound the same on a test drive, so if the suspension was repaired at a garage, ask for the invoice and listen to the car.

The engine warning light comes on, the engine runs badly, and the fault code points at oil pressure, although the most common cause is the sensor itself, not that the engine really has no oil pressure. Replacing the sensor is the smaller and more common repair, but you cannot decide that just by looking, because only a measurement can rule out low oil pressure, and if the pressure really is low the engine is damaged. Do not buy the car without a fault code read.

With the air conditioning on, a whistling noise comes from the dashboard, and the cause is the expansion valve, which meters the refrigerant, so the compressor has not failed and the gas has not run out. Most places first suggest a recharge, but a recharge does not stop the noise: the noise comes back, and you pay for a recharge that does not help.

The dash shows "Error: Workshop! Only leave vehicle in position P" with an audible warning. The message appears in whatever language the car is set to, for example "Fehler: Werkstatt! Fahrzeug nur in Stellung P verlassen" in German.