| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. |
Note. Sensor No. 1 refers to sensor closest to engine block. Sensor No. 2 refers to sensor furthest from engine block.
Circuit Description
The oxygen sensor monitors exhaust gas oxygen content and delivers an input signal to ECM. The ECM uses input signal to determine fuel injection system operation. DTC is set when sensor does not output a rich condition once engine is at normal operating temperature, engine speed of 1500 RPM or more, and vehicle speed is 25-62 MPH for at least 2 minutes. Possible causes are
- Open or short in oxygen sensor circuit.
- Oxygen sensor.