Audi A3

All four injectors in the 1.6 TDI CAYB can fail around 100,000 km. Since Bosch/Siemens does not offer individual replacement, all four must be changed at once. Poor fuel quality significantly accelerates wear.

Symptoms: Juddering under acceleration, exhaust smoke, starting problems, rough idle, elevated fuel consumption

The EGR valve carbons up considerably faster due to increased EGR operation following the diesel software update. Sticking or seized valves cause juddering, power loss, and limp mode. Cooler cracks allow coolant to enter the exhaust tract.

Symptoms: Rough idle, black smoke, engine power loss, limp mode, fault code P0401

The DPF on the 1.6 TDI becomes blocked with predominantly short-trip use, as regeneration temperature is not reached. Faulty EGR valves and injectors accelerate soot loading. Professional cleaning or replacement is then required.

Symptoms: DPF warning light, elevated fuel consumption, engine limp mode, power loss at low rpm

On the 1.6 TDI (built up to 09/2014), the water pump regulating valve can fail. Coolant temperature rises to 130°C, triggering the red warning light. VW TPI 2041955 documents the issue. Secondary engine damage is possible.

Symptoms: Red coolant temperature warning light, engine overheating, coolant loss without visible leak

In the 2.0 TDI with 140/170 PS (built before April 2008) thermal stress can cause cracks in the cylinder head. Coolant loss, overheating and expensive engine damage result.

On 2008–2009 build years a sudden power loss can disable safety-critical systems such as ABS and ESP. The cause is a defective control unit ground point.

Rear springs frequently break in the region of the spring seat, often due to corrosion starting there. The break often goes unnoticed as it produces no noise.

Rust forms on rear wheel arches, side sills and the tailgate on older examples. Typical spots are the transitions between wings and sills.