Oxygen Sensor: Testing and Inspection

An open Heated Oxygen Sensor (HO2S) should set a Diagnostic Trouble Code (DTC) 13. A constant low voltage in the sensor circuit should set a DTC 44. A constant high voltage in the circuit should set a DTC 45. DTC 44 and DTC 45 could also be set as a result of fuel system problems. The integral heater in the sensor will not set a DTC but is diagnosed in DTC 13.
For conditions that can cause a lean system refer to DTC Chart 44.
For conditions that can cause a rich system refer to DTC Chart 45.
All the above DTC charts can be found at Procedures / Diagnostic Charts . Testing and Inspection