Code 13 - Oxygen (O2) Sensor Circuit
Code 13 will set: at least 2 minutes after engine starts, with O2 sensor signal voltage between .35 and .55 volts for more than one minute, and TPS signal above 6% (.8 to 1.2 volts, about 1200 RPM). ECM supplies 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 from about one volt (exhaust rich) down to about .10 volt (exhaust lean).
The sensor is like an open circuit and produces no voltage when it is below about 600°F (310°C). An open sensor circuit or cold sensor causes open loop operation.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- Grounding diagnostic terminal with engine running activates "Field Service Mode", which allows ECM to confirm either open or closed loop operation using the "SERVICE ENGINE SOON" light.
- Verifies no additional codes stored, and that Code 13 is intermittent.
- Simulates lean exhaust. If ECM and wiring are okay, ECM will see lean condition and turn "SERVICE ENGINE SOON" light off for at least 15 seconds after engine start, then flash "open loop". Light remaining off for a longer period of time before flashing open loop is normal.