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Home >> Buick >> 1989 >> Reatta >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> 3.8L (3800 VIN [C]) ECM Tests W/Codes >> Diagnostic Circuit Check >> Code EO13, Open Oxygen Sensor Circuit >> Notes
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Code EO13, Open Oxygen Sensor Circuit: Notes

Fig 1: Code EO13, Schematic - Open Oxygen Sensor Ckt
G111367
NOTE: Test numbers refer to numbers on diagnostic chart.
  1. Code EO13 will set under the followig conditions:
    • No Codes EO21 or EO22.
    • Engine at normal operating temperature.
    • Engine run time greater than 40 seconds.
    • O2 signal voltage ED07 display, steady between .35 and .55 volt.
    • Throttle position sensor greater than .55 volt.
    • All conditions must be met for about 30 seconds.

    If the listed conditions for a Code EO13 exists, the system will not go to "closed loop".

  2. This will determine if the sensor or the wiring is the cause of the Code EO13.
  3. In performing this test, use only a high impedence 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 (600 mV).