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:
Oxygen sensor open or short circuit.
Air/Fuel Ratio Sensor (AFS).
AFS open or short circuit.
Sunday, November 22nd, 2009 AT 4:42 PM