Circuit Description

Heated oxygen sensor monitors exhaust gas oxygen content and delivers an input signal to ECM. ECM uses input signal to determine fuel injection system operation. Heated oxygen sensor includes a heater. DTC is set when heated oxygen sensor No. 2 voltage remains at .4 volt or more, or .5 volt (except California emissions) or .6 volt (California emissions) or less during vehicle operation (25 MPH or more), once engine is at normal operating temperature. Possible cause is:

• Heated oxygen sensor No. 2 circuit is open or shorted.
• Defective heated oxygen sensor No. 2.