Audi Known Faults

Germany

Known Faults

Models

A3

1996–present

35 faults

A4

1994–present

5 faults

Q5

2008–present

4 faults

Most Reported Faults

DPF Blockage

Moderate

2008-201540,000–90,000 miles£200–£1400

The A4 B8 TDI is frequently used as a company car on short local journeys rather than motorway runs. DPF blockage is the most common ownership complaint.

Turbocharger Failure

Severe

2008-2015100,000–180,000 miles£650–£1100

Turbocharger failure on the B8 A4 TDI mirrors the wider VAG TDI pattern — oil sludge in the feed pipe causes bearing failure, often presenting as a sudden loss of boost.

Timing Belt Failure

Critical

2008-2015100,000–140,000 miles£400–£700

The B8 A4 2.0 TDI uses a timing belt with a 140,000-mile service interval. Many specialists recommend 100,000 miles. Belt failure is catastrophic on this interference engine.

EGR Cooler Failure and Coolant Loss

Severe

2008-201570,000–140,000 miles£500–£900

EGR cooler failure is common on the B8 A4 TDI. Internal corrosion allows coolant to leak into the intake — initially causing rough running and white smoke.

Injector Failure

Severe

2008-2015100,000–200,000 miles£350–£1200

High-mileage A4 B8 TDIs suffer injector wear, causing rough running, smoke and diesel contamination of engine oil.