Diagnostic Aids

Normal "Scan" tester voltage varies between 100 and 999 mV while in "closed loop". Code 13 will set in one minute if voltage remains between .35-.55 volt; however, system will go "open loop" in about 15 seconds.

Fig 1: Code 13: Open O2 Sensor Ckt Diag (5.0L & 5.7L)

Fig 2: Code 13: Open O2 Sensor Flow Chart