Circuit Description

Heated oxygen sensor monitors exhaust gas oxygen content and delivers input signals to Engine Control Module (ECM). Heated oxygen sensor is located on exhaust pipe, behind catalytic converter. Heated oxygen sensor may also be referred to as oxygen sensor (bank No. 1 sensor No. 2). ECM uses input signals to determine fuel injection system operation. On California emission vehicles, DTC is set when heated oxygen sensor output voltage remains at .45 volt or more, or .60 volt or less when vehicle is driven at 31 MPH with engine at normal operating temperature. On except California emission vehicles, DTC is set when heated oxygen sensor output voltage remains at .40 volt or more, or .50 volt or less when vehicle is driven at 31 MPH with engine at normal operating temperature. On all models, possible causes are:

• Heated oxygen sensor circuit is open or shorted.
• Defective heated oxygen sensor.