Possible causes

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

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)

FORD Technical Service Bulletins for P0642 code