Circuit Diagnosis

^ Oxygen sensor heater resistance should be greater than 30 ohms at 750°F (400°C).

^ Open Circuit:

Disconnect the harness at the PCM and the sensor. Check for continuity in the suspect circuit (example: "A" to "B" from the "Basic O2 Sensor Circuit" diagram).

^ Short Circuit:





Disconnect the harness at the PCM and the sensor. Check to see if there is continuity to ground in the suspect circuit (example: "A" to ground from the "Basic O2 Sensor Circuit" diagram).