Heated Oxygen Sensor (HO2S 1) Testing

The heated oxygen sensor circuit, if open, should set a Diagnostic Trouble Code (DTC) P0134 and the Scan tool 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 P0131 HO2S Circuit Low Voltage Bank 1 Sensor 1 or DTC P0132 HO2S Circuit High Voltage Bank 1 Sensor 1 or DTC P0134 HO2S Insufficient Activity Bank 1 Sensor 1. Refer to System Diagnosis / Diagnostic Tables for testing information. Testing and Inspection