The smallest diesel engine VW sell with a DPF is also the most prone to blocking it — the 1.2 TDI Polo simply cannot generate enough heat from urban driving for reliable regeneration.

Injector Failure

Moderate

2009-201480,000–150,000 miles£250–£600

Injector wear on the 1.2 TDI causes rough running and smoke. The three-cylinder engine runs with high injection pressures that accelerate injector wear.

Timing Belt Failure

Critical

2009-20141–60,000 miles£280–£500

The 1.2 TDI Polo has a timing belt that must be replaced at 60,000 miles or 4 years. Many owners are unaware of this interval — belt failure destroys the engine on this interference unit.

Timing Chain Rattle on Cold Start

Moderate

2009-201770,000–140,000 miles£400–£700

The 1.4 petrol Polo uses a timing chain, but the tensioner weakens with age causing a cold-start rattle. Left unchecked, chain stretch causes valve timing issues.