Circuit/System Verification
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- Ignition ON, observe the scan tool DTC information. Verify there is no other HO2S or fuel trim DTC set.
- If any other HO2S or fuel trim DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Verify that none of the following conditions exist:
- The air intake duct for being collapsed or restricted.
- The air filter for biting dirty or restricted.
- Objects blocking the throttle body.
- Excessive fuel in the crankcase. Change the engine oil as necessary.
- Rich fuel injectors-Refer to Fuel Injector Diagnosis (CH47976) , Fuel Injector Diagnosis (J39021 or Scan Tool) .
- High fuel system pressure-Refer to Fuel System Diagnosis (Without FPCM) , Fuel System Diagnosis (FPCM) .
- Fuel that is contaminated-Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
- Fuel saturation of the evaporative emissions (EVAP) canister
- Stuck open or leaking EVAP purge valve
- Restricted exhaust-Refer to Symptoms - Engine Exhaust
- Incorrect PCV system operation-Refer to Crankcase Ventilation System Inspection/Diagnosis
- If you find any of the above conditions, repair as necessary.
- Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.