The folded edge rusts from the inside out: by the time it shows on the paint, the metal is already weakened. And a bonnet that has been repainted but not repaired brings the same thing back within a few years.

The water stands under the spare wheel well, the floorpan corrodes, and the connectors running in the boot can get soaked. If the rear washer does not work, check where the water went.

The message points at the gearbox, but the fault is not there. A tiny switch sits in the module under the selector lever and signals that the lever is in park (P). Its contact wears and can also burn. That makes the signal unreliable, and the car warns you. The fault codes appear as 617752, P173400 or B116229.

At first it is intermittent. Sometimes the message comes up, sometimes not, so a short test drive easily misses it. Later it becomes permanent, and the gearbox can drop into limp mode.

This fault looks more expensive than it is. The maker released a separate retrofit switch kit for it (5Q0713128A for the black module, 3Q0713128 for the white one), which can be fitted in half an hour. The kit costs 70 to 100 pounds. At a franchised dealer, however, the whole selector lever module sometimes gets replaced, which costs 626 to 1,000 pounds there. So the difference between the two routes is roughly tenfold.

The affected group is post 2013 MQB platform Volkswagen, Audi, Seat and Skoda cars with a DSG gearbox. The switch is in these gearboxes, because that is what these cars have in common. The part itself is not part of the gearbox but of the module under the lever.

There are four mechanisms in four doors. If a window moves on its own, a locked car can be left open.

In cold, damp weather, on startup, the engine runs unevenly, misfires under acceleration, and the engine warning light flashes or stays on. Do not keep driving with the light flashing: the unburnt fuel destroys the catalytic converter.