Oxygen Sensor: Testing and Inspection

OXYGEN SENSOR TESTING
A Tech 1 scan tool has several positions that indicate the state of the exhaust gases. These positions indicate Oxygen Sensor (O2S) voltage, short term fuel trim, and long term fuel trim.

A problem in the O2S circuit should set a Diagnostic Trouble Code (DTC) 13 (open circuit), DTC 44 (lean exhaust indication), or DTC 45 (rich exhaust indication).