IsItAGoodCar
Reliability Guide

Common Problems with the
2004 Audi A6 Mk3 (C6)

The launch year brought a major step up in tech and refinement over the C5. Early cars carry the highest risk of V6 TDI timing chain tensioner failure and Multitronic CVT gearbox issues, making careful inspection essential.

What changed for 2004

  • •Launch with 2.0 TDI, 2.4, 2.7 TDI, and 3.0 TDI engines
  • •New Multitronic CVT gearbox option
  • •Updated MMI infotainment system
  • •Adaptive air suspension option

Common MOT watch-outs

  • !V6 TDI timing chain tensioner rattle on cold start
  • !Multitronic CVT chain and control unit failure
  • !DPF clogging on town-driven diesels
5
Known Issues
3
Serious
2
Moderate
0
Minor

All Known Issues

TDI Timing Chain Tensioner Failure

SeriousEngine

The hydraulic tensioners for the timing chains can fail, causing a loud rattle on start-up.

Est. Repair Cost: £800–£1,500

Multitronic CVT Chain and Control Unit Failure

SeriousGearbox & Transmission

Front-wheel-drive models with the Multitronic CVT can suffer chain stretch, cone damage and control board failure, especially if fluid changes have been skipped.

Est. Repair Cost: £1,000–£3,500

Adaptive Air Suspension Leaks

SeriousSuspension & Chassis

Cars with optional air suspension develop leaks in the air struts or bags, causing the car to sag and the compressor to overwork and eventually fail.

Est. Repair Cost: £700–£2,000

DPF Clogging and EGR Faults

ModerateExhaust & Emissions

Town-driven 2.0 TDI and 2.7 TDI models block their DPFs and develop EGR cooler leaks, causing warning lights and limp mode.

Est. Repair Cost: £250–£1,200

MMI Freeze and Electrical Gremlins

ModerateElectrics & Electronics

The MMI infotainment system can freeze or reboot, and various electrical sensors, parking modules and climate control motors can fail.

Est. Repair Cost: £0–£600

Buying Tips for 2004 Audi A6 Mk3 (C6)

  • ✓Insist on a stone-cold start to check for V6 TDI timing chain rattle
  • ✓Avoid Multitronic CVT cars without perfect service history
  • ✓Check all MMI functions including rear wash-wipe module
2005–2008
Check a 2004 Audi A6 Mk3 (C6) by Registration