Oxygen Sensor: Testing and Inspection

The heated oxygen sensor circuit, if open, should set a Diagnostic Trouble Code (DTC) P0134 and the Tech 1 will display a constant voltage between 350 - 550 mV. A constant voltage below 250 mV in the sensor circuit should set DTC P0131, while a constant voltage above 750 mV in the circuit should set DTC P0132. DTC P0131 and DTC P0132 could also be set as a result of fuel system problems. Refer to DTC charts for conditions that can cause a lean or rich system. Testing and Inspection