Circuit/System Testing
- Engine operating, move the related HO2S harnesses for the appropriate HO2S 2 between the HO2S harness connector and the engine control module (ECM) while monitoring the appropriate scan tool HO2S 2 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 2.
- Ignition ON, verify that the HO2S 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 (w/LLT) .
- 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 (with Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (w/o Special Tool) .
- 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 2.