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Home >> Pontiac >> 1989 >> Firebird Formula, 5.0 F, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> 5.0L/5.7L PFI Tests W/Codes >> Diagnosis & Testing >> Code 13: Open Oxygen Sensor Circuit >> Notes

Code 13: Open Oxygen Sensor Circuit: Notes

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. Code 13 will set when the following conditions occur:
    • Engine at normal operating on temperature.
    • At least 2 minutes elapsed since start-up.
    • Oxygen signal voltage steady between .35 and .55 volt.
    • Throttle angle greater than 3-6 percent (about .3 volt greater than closed throttle voltage).
    • All conditions must be met for about 60 seconds.

    If conditions for a Code 13 exist, the system will not go "closed loop".

  2. This test will determine if the sensor, wiring or ECM is the cause of Code 13.
  3. When conducting this test, use only a high impedence (10 megohm) digital volt/ohmmeter. This test checks the continuity of circuits No. 412 and 413. If circuit No. 413 is open the ECM voltage on circuit No. 412 will be greater than .6 volt.