Symptoms

- Engine Light ON (or Service Engine Soon Warning Light)

Possible Causes

- ECM Short circuit condition - Shorted sensor on 5 volt circuit - Failed ECM

Tech Notes

There is a factory service bulletin for the P0642 code for the following models: Audi A3 2005 and 2007 Audi A4 2005 and 2007 Audi A4 Cabriolet 2007 Audi TT 2008 Audi P0642 Code Serive Bulletin

Description

The ECM has detected that the 5 volt reference voltage is too low