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Home >> Geo >> 1989 >> Spectrum 2D Hatchback, Standard >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Tests W/Codes >> Code 13, O2 Sensor Circuit Open >> Code 13, Oxygen Sensor Circuit Open Circuit
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Code 13, Oxygen Sensor Circuit Open Circuit

The ECM supplies approximately .45 volt between ECM terminals 3 and 20. If reading is taken with a 10-megohm DVOM, reading may be as low as .32 volt. The O2 sensor produces a varying voltage as engine reaches normal operating temperature. Voltage will vary from .10-1.0 volt. The O2 sensor does not produce a voltage until sensor reaches 600°F (316°C). When sensor is less than this temperature, an "Open Loop" condition exists. Code 13 will set with engine at normal operating temperature, at least 5 minutes of engine run time after engine start and part throttle, O2 sensor signal steady between .35-.55 volt, throttle is off idle and all conditions present for approximately 60 seconds. Computer system will not go into "Closed Loop" when these conditions exist.

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. This determines if O2 sensor is at fault or if ECM and wiring are faulty.
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