General notes on ignition system

The engine control module is equipped with On Board Diagnostic (OBD).
For trouble-free operation of the electrical components a voltage of at least 11.5 V is necessary.
During some of the tests it is possible that the control module will detect and record a fault. The Diagnostic Trouble Code (DTC) memory must therefore be checked and if necessary erased when all tests and repair work have been completed.
After completing fault finding, repairs or component tests, it is possible that the engine will start, run for a short period and then cut out. If this happens it may be that the immobilizer is blocking the engine control module. In such cases the DTC memory must be checked and if necessary the control module must be adapted.

CAUTION:

On vehicles equipped with Audi Telematics by OnStar®, switch-off the emergency (back-up) battery for the Telematic/Telephone Control Module prior to disconnecting the vehicle battery. Switch-on the emergency (back-up) battery after reconnecting the vehicle battery. Refer to 91 - COMMUNICATION .