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Home >> Buick >> 1991 >> Reatta 2D Convertible >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - Pcm/BCM >> Diagnostic Flow Charts For ECM/Pcm Codes: EO13 To EO69 >> Code EO13, Open Oxygen Sensor Circuit >> Notes
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Code EO13, Open Oxygen Sensor Circuit: Notes

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. This tests if problem still exists. Vehicle cannot enter closed loop mode if oxygen sensor circuit is open. Code EO13 indicates an open in the O2 sensor circuit. Code will set if:
    • Engine is at normal operating temperature.
    • Neither Code EO21 nor Code EO22 are stored.
    • O2 sensor voltage is constant within a specified range (.34-.55 volt).
    • Throttle angle is greater than idle.
    • A precalibrated amount of time has elapsed since start-up.
    • All conditions have existed for a precalibrated amount of time.
  2. Determines if O2 sensor, wiring or control module is at fault. If wiring is good, grounding oxygen sensor wire will cause .45 volt reference supplied by the control module to pull low.
  3. This tests O2 sensor circuit wiring. Use only a high impedance (10-megohm minimum) digital voltmeter.