Code 13 - Open Oxygen Sensor Circuit
The ECM supplies about .45 volt between terminals No. 9 and No. 14. Voltage may read as low as .32 volt when measured with a 10-megohm digital voltmeter. The O2 sensor varies voltage within a range of about one volt (rich exhaust) to about .1 volt (lean exhaust). Code 13 indicates an open in the O2 sensor circuit under the following conditions:
- Engine at normal operating temperature.
- O2 sensor voltage is within a specified range (.35-.55 volt).
- Throttle angle greater than zero percent (off idle).
- More than 2 minutes have elapsed since start-up.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- This test checks to see if problem still exists. Normal dwell reading will vary, indicating fault is not present. Fixed dwell indicates fault.
- By grounding the O2 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" from the ECM.
- This test checks O2 sensor. With the rich command, O2 sensor should read a high voltage, greater than .8 volt. If O2 sensor functions, fault is in sensor connections.