DTC 13

Fig. 003 - WIRING DIAGRAM for Code 13 Open Oxygen Sensor Circuit. VIN 3, VIN 9:

CODE 13, OXYGEN SENSOR CIRCUIT

Code 13 is set when the voltage at terminal D7 of the ECM:
a. Stays within a range of .35 to .55 volts;
b. The TPS is above a specified value; and
c. The engine has run a specified time after start.
The ECM supplies a voltage of about .45 volt between terminals D6 and D7. (If measured with a 10 megohm digital voltmeter, this may read as low as .32 volts.) The O2 sensor varies the voltage within a range of about 1 volt if the exhaust is rich, 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 360°C (600°F). An open sensor circuit or cold sensor causes open loop operation.

Fig. 002 Chart - Code 13 Open Oxygen Sensor Circuit:

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 "SERVICE ENGINE SOON" light.
Code 13 will set:
a. At least 2 minutes engine run time after start.
b. O2 signal voltage steady between .35 and .55 volts for more than one minute.
c. Throttle position sensor signal above 6% (.9 to 1.0 volt).
2. This step verifies no additional codes stored and the stored Code 13 is intermittent. See Section B.
3. This step simulates a lean exhaust. If the ECM and wiring are OK the ECM will see the lean condition and turn the "SERVICE ENGINE SOON" light off for at least 15 seconds after engine start.