Code 13 - Open Oxygen (O2) Sensor Circuit: Notes

A voltage of about .45 volt is supplied between terminals "YC14" and "YC15" by ECM. If measured with 10 megohm digital voltmeter, reading may be as low as .32 volt. Voltage signal from O2 sensor will range from about one volt (rich signal), to about .10 volt (lean signal). Oxygen sensor will produce no voltage when temperature is less than 600°F (316°C). Vehicle remains in "open loop" if an open circuit exist, or if O2 sensor temperature is less than given value.

The following conditions must exist to set a Code 13:

• Engine running at least 40 seconds after start.
• Engine coolant temperature greater than 40.1°F (42.5°C).
• Code 21 or 22 must not be set.
• Oxygen sensor voltage steady between .34 and .55 volt.
• TPS signal greater than 6 percent for more time than less than 6 percent, or about .3 volt greater than closed throttle voltage.
• Conditions must be met and held for at least 20 seconds.

1. 2) This test will indicate whether sensor is faulty, or if wiring and/or ECM is cause of Code 13.
   NOTE: Use only high impedance digital volt/ohmmeter for this test.
2. 3) This test checks for continuity of circuits No. 412 and 413. If circuit No. 413 is open, ECM voltage on circuit No. 412 will be greater than .6 volt (600mV).