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Home >> Isuzu >> 1990 >> Trooper S, 2.6 E, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 2.8L >> Diagnostic Circuit Check >> Code 13: O2 Sensor Circuit Open >> Notes
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Code 13: O2 Sensor Circuit Open: Notes

NOTE: Test numbers refer to test numbers on diagnostic chart.
  1. Code 13 will set if the engine is at normal operating temperature, at least 2 minutes engine running time has elapsed since start, oxygen signal voltage is steady between .35 and .55 volt, engine speed is greater than 1600 RPM and throttle position sensor signal greater than 5 percent (about .3 volt more than closed throttle). All conditions must be met for about 60 seconds. If the conditions for a Code 13 exist, system will not go "closed loop". An open sensor circuit or cold sensor causes "open loop" operation.
  2. This will determine if sensor, wiring or ECM is the cause of the Code 13.
  3. In doing 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, ECM voltage on circuit No. 412 will be greater than .6 volt.
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