The combined housing of the water pump and the thermostat is plastic, and it is bolted directly to the hot engine block. The many heat and cool cycles warp it, it becomes brittle, and then it develops a hairline crack: the fault is almost always the housing, not the pump itself. The signs are slowly disappearing coolant with no visible puddle, the coolant level light, a sweet smell from the engine bay, and later a pink stain under the car. The repair means replacing the pump and the housing together, and the intake manifold has to come off for it: 4 to 6 hours of work. It shows up on model years 2015 to 2025.

The crankcase ventilation (PCV) of the third generation 1.8/2.0 TSI fails less often than its predecessors, but it is not faultless. After sustained full load acceleration, under hard braking, the return branch of the ventilation can be overloaded, and the oil ends up in the intake instead of draining. The symptoms are oil consumption, blue smoke after load, and deposits in the intake.

The piston of a rear caliper with an electric parking brake cannot be wound back by hand: the caliper has to be put into service mode with a diagnostic tool. Where that was bypassed, the actuator of the caliper is damaged, and soon after a disc replacement the caliper needs replacing too.

On four wheel drive cars the oil and filter of the Haldex clutch are wear items and have to be replaced, and that service is the one most often skipped. If it is skipped, the rear axle engages erratically, it clicks in corners, and eventually the clutch and the pre-charge pump fail. The pump is the expensive part.

The seven speed dry DSG often starts shifting hesitantly as early as 30,000 to 50,000 km: it does not shift smoothly, sometimes it cannot find the gear, and it jerks worst in slow, congested traffic. The cause is wear of the clutch pack and the mechatronics unit. Many people skip the oil change because they believe it is a lifetime fill, and most DSG faults come from that.

The crankcase breather carries the vapour that forms inside the engine back to the intake, and a rubber membrane regulates the pressure. Oil and heat harden this membrane until it tears, and from then on the intake draws air through the hole in it. The engine control unit does not measure that air, so the mixture goes wrong: the engine shakes at idle, stumbles when accelerating, and the fault memory gets P2279 for an intake system leak. In the other direction oil starts towards the intake, which leaves an oily film in the intercooler and on the intake pipe and speeds up the carbon build-up on the intake valves. The audible sign is a whistling or hissing noise from the engine bay, loudest at idle. The tear is reported between 60,000 and 90,000 km. On the first and second generation the breather is a separately replaceable valve (factory number 06H 103 495 AK) and costs between 80 and 400 euro; from the third generation it is built into the cam cover, so there the cover is replaced. The maker issued three versions up to 2016, and fitting the pressure variant that does not belong to the engine brings the same symptom back.

The stop-start drops out as early as 20,000 to 35,000 km, typically on the 1.0 TSI and 1.6 TDI versions. The cause is the condition of the battery.

The per cylinder ignition coil of these direct injection, turbocharged petrol engines fails. According to the Haynes service material this and similar simple electrical faults account for roughly eighty per cent of workshop visits.