Will not start because of the immobiliser on the Audi A4 (B6) and A6 (C5)

Engine / equipment

Audi A4 2000–2004 (B6) and A6 1997–2004 (C5), all versions

Period mentioned

1997–2004

Symptoms

The car will not start because the immobiliser blocks it. On the A6 the central locking, windows and battery also often fail.

Possible cause described

AUTO BILD says that on the 2000–2004 A4 a faulty immobiliser often prevents starting, and that the repair is a new instrument cluster (which houses the immobiliser), for about €500. On the 1997–2004 A6 it lists the immobiliser, central locking and window regulators among the main culprits for electrical faults, plus a battery that often fails.

Check for the garage

First test the battery: with low voltage the immobiliser fails too. Try the spare key. If it still will not start with either key, the garage diagnoses the immobiliser in the cluster with Audi equipment before replacing the cluster, because the keys have to be matched.

Cost cited in the source

About €500 for the instrument cluster (AUTO BILD, 2008).A rough figure from the original database, not an up-to-date quote.

Sources from the original database