FixVault

Circuit/System Testing

  1. With the engine running at operating temperature, observe the HO2S Heater parameter with a scan tool and manipulate the related wiring and connectors.
    • If manipulation does affect the parameter then repair the harness or connector.
  2. With the ignition ON, the engine OFF, and the sensor disconnected, connect a test lamp between the HO2S sensor heater supply voltage circuit and ground. The lamp should illuminate.
    • If the lamp does not illuminate then test the voltage supply circuit for high resistance or for a short to ground.
  3. With the ignition OFF, connect a test lamp between the HO2S sensor low control circuit and battery voltage. The lamp should not illuminate.
    • If the lamp illuminates then test the low control circuit for a short to ground or a faulty control module.
  4. With the engine RUNNING, leave the test lamp connected from the previous step. The lamp should flash or be ON steady.
    • If the test lamp is not ON steady or flashing, then test the control circuit for a short to voltage, high resistance, or a faulty control module.
  5. If the PCM and all circuits test normal, replace the HO2S sensor.