The front suspension of the B5 is multi link, and the bushes of the arms wear quickly; the upper arms go first. The signs are knocking over potholes, vague steering and uneven tyre wear. Owners typically replace them more than once over the life of the car.

Leaves and debris block the drains of the water collector under the windscreen. The standing water runs in through the lid of the pollen filter housing and its perished seal, into the cabin, under the carpet. That is where the comfort electronics control unit sits, and it corrodes when wet: the central locking, the window regulators, the interior lighting, the mirrors and the fuel flap release start dropping out, typically intermittently and after wet weather. The control unit is the expensive part: whoever replaces only the unit but does not clean the drain destroys the new one too.

The per cylinder ignition coils fail early: jerking, misfire, a flashing engine warning light, limp mode. Typically several age at once, and after a replacement the new ones can go early too. The phenomenon occurs on every B5 engine, not only the turbocharged ones.

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.

From the late nineties to around 2006, petrol engines used a secondary air pump to blow fresh air into the exhaust on a cold start, so the catalytic converter reaches operating temperature faster. The impeller of the pump rusts or its bearing seizes, soot clogs the combination valve (N112), and the rubber hoses crack. The control unit then stores the `P0411` code. It barely affects driving, but the engine warning light is on, and the emissions test can fail because of it, and the roadworthiness test with it.