Note. Sensor No. 1 refers to sensor closest to engine block. Sensor No. 2 refers to sensor furthest from engine block.
Circuit Description
The ECM monitors heated oxygen sensor located after converter to determine if converter performance has deteriorated. If converter is functioning properly, heated oxygen sensor waveform switches back and forth between rich and lean more slowly. DTC is set when both heated oxygen sensors have same amplitude after vehicle is driven for 5 minutes at 20-50 MPH. Possible causes are
- Catalytic converter.
- Oxygen sensor open or short circuit.
- Oxygen sensor.
- Air/Fuel Ratio Sensor (AFS).
- AFS open or short circuit.