| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. |
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. Sensors include heater. DTC is set when sensor does not output a rich condition once engine is at normal operating temperature, engine speed is 1500 RPM or more, and vehicle speed is at least 25 MPH for at least 2 minutes. Possible causes are
- Open or shorted oxygen sensor circuit.
- Heated oxygen sensor.
Note. Bank No. 1 refers to bank that includes cylinder No. 1. Bank No. 2 refers to bank without cylinder No. 2. Sensor No. 1 refers to sensor closest to engine block.