DTC 13

Fig. 036 Code 13 Open Oxygen Sensor Circuit:

Fig. 037 - Wiring Diagram for Code 13 Open Oxygen Sensor Circuit. VIN Z:

CODE 13, OXYGEN SENSOR CIRCUIT

The ECM supplies a voltage of about .45 volt between terminals "D7" and "D6". (If measured with a 10 megohm digital voltmeter, this may read as low as .32 volts.) The O sensor varies the voltage within a range of about 1 volt if the exhaust is rich,
2 down through about .10 volt if exhaust is lean.
The sensor is like an open circuit and produces no voltage when it is below about 310°C (600°F). An open sensor circuit or cold sensor causes open loop operation.
This engine is equipped with an electrically heated oxygen sensor. The sensor is energized by the fuel pump relay, and remains on as long as the engine is running. Failure of the heating element or feed or ground circuits may cause a Code 13 to be set at idle or low RPM.
Code 13 will set:
a. At least 2 minutes engine time after start.
b. O signal voltage steady between .35 and .55 volts for more the one minute.
2
c. Throttle position, off idle about 1200 RPM.
1. Grounding the diagnostic terminal with the engine running enables the "Field Service Mode", which allows the ECM to confirm either open or closed loop operation using the "CHECK ENGINE" light.
2. This step verifies no additional codes stored, and that stored Code 13 is intermittent. See DIAGNOSIS BY SYMPTOM.
3. Check for proper operation of oxygen sensor heating control circuit.
4. Check for an internal open or short to ground in the oxygen sensor heating element.
5. This step simulates a lean exhaust. If the ECM and wiring are OK the ECM will see the lean condition and turn the "CHECK ENGINE" light off for at least 15 seconds after engine start, and then flash "open loop". It should be considered normal if the light remains off for a longer period of time before flashing open loop.