Code 13 - Oxygen Sensor Circuit
Code 13 indicates an open in the oxygen sensor circuit with the following conditions:
- Oxygen sensor voltage is within a specified range.
- Above a specified TPS value.
- More than specified time after engine has warmed up.
The ECM supplies about .45 volt between terms. "9" and "14." Voltage may read as low as .32 volt when measured with a 10 megohms digital volt-ohm meter. The oxygen sensor varies the voltage within a range of about 1 volt (rich exhaust) to about .1 volt (lean exhaust).
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- This test checks to see if problem still exists. Fixed dwell indicates fault.
- By grounding the oxygen sensor circuit to the ECM, a "low voltage (lean) signal" is sent to the ECM. This should result in a "full rich (low dwell) command."
- This test checks oxygen sensor. With the rich command, the oxygen sensor should read a high voltage, over .8 volt. If the oxygen sensor functions, fault is in the connections to the sensor.
- Checks for an open in the ECM-oxygen sensor ground circuit. Normal voltage is below 1 volt if the circuit is complete. The worse the connection is, the higher the voltage will read.
- This grounds the oxygen sensor signal wire at the ECM. Dwell should go to below 10°, since this is a "low voltage signal" indicating lean exhaust. No change indicates a problem at the ECM connections, or the ECM.