Circuit/System Testing
- Engine operating, move the related HO2S 2 harnesses for the appropriate sensor between the HO2S 2 harness connector and the ECM while monitoring the appropriate scan tool HO2S voltage parameter. Verify that the HO2S parameter does not change abruptly while moving the related harnesses.
- If the HO2S parameter does change abruptly while moving the related harnesses repair the circuit as necessary.
- Ignition OFF, disconnect the harness connector at the appropriate HO2S.
- Ignition ON, verify the scan tool HO2S 2 parameter is between 400-520 mV.
- If greater than the specified range, test the signal circuit terminal B for a short to voltage. If the circuit/connections test normal, replace the ECM.
- Verify that none of the following conditions exist:
- Rich fuel injectors - Refer to Fuel Injector Solenoid Coil Test .
- Water intrusion in the HO2S harness connector
- High fuel system pressure - Refer to Fuel System Diagnosis .
- Fuel that is contaminated - Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
- A collapsed air intake duct
- A restricted air filter element
- Exhaust system restrictions
- Excessive fuel in the crankcase
- An engine mechanical condition - Refer to SYMPTOMS - ENGINE MECHANICAL .
- If you find any of the above conditions, repair as necessary.
- If all circuits/connections test normal, replace the appropriate HO2S.