DTC 13

Code 13 - Open Oxygen Sensor Circuit:

Wiring Diagram For Code 13 - Open Oxygen Sensor Circuit:

CODE 13 - OPEN OXYGEN SENSOR CIRCUIT


Circuit Description:

Code 13 will set:

^ At least 2 minutes engine time after start.
^ O2 signal voltage steady between .35 and .55 volts for more than one minute.
^ Throttle position sensor signal above 6% (.8 to 1.2 volt).

The ECM supplies a voltage of about .45 volt between terminals "8" and "15". (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 310~C (600~F). An open sensor circuit or cold sensor cause open loop operation.


Test Description:

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 Symptoms - No Trouble Codes Stored.

3. This step simulates a lean exhaust. If the ECM and wiring are OK the ECM will see the lean condition and tum 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.