General information: Notes

All A8 from m.y. 2000 are equipped with Immobilizer Generation III.

Generation III has the same functionality as the previous version. However, in addition to the normal data exchange between the immobilizer control module and ignition key, Gen. III includes data exchange between the immobilizer control module and Engine Control Module (ECM).

Data exchange between the Immobilizer control module and ECM takes place over the vehicle CAN-Bus network.

NOTE:

For Immobilizer III, the Engine Control Module (ECM) is actively incorporated into the evaluation and monitoring. The control module for immobilizer is integrated into the instrument cluster.
For immobilizer III, the keys are marked with an inscribed "W". The code consists of a fixed code and a variable code portion.

Fig 1: Identifying Keys Marked With Inscribed "W"

Courtesy of AUDI OF AMERICA, INC.