Possible causes

– Faulty Engine Control Module (ECM)
– ECM harness is open or shorted
– ECM circuit poor electrical connection
– Shorted sensor on 5 volt circuit

Tech notes

There is a factory service bulletin for the P0642 code for the following models:

2005-2007 Audi A3
2005-2007 Audi A4
2007 Audi A4 Cabriolet
2008 Audi TT
Audi Factory Service Bulletin OBDII Code P0642

When is the code detected?

The Engine Control Module (ECM) has detected the sensor 5 volt reference circuit voltage is lower than expected

Symptoms

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

AUDI Technical Service Bulletins for P0642 code