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Home >> Geo >> 1990 >> Storm Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Code 13, Oxygen Sensor Circuit (Non-Heated O2 Sensor Only) Open Or Grounded Circuit >> Diagnostic Aids
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Diagnostic Aids

Normal scan voltage varies between .1-1.0 volt (100-999 mV) while in closed loop. Code 13 sets within one minute, if voltage remains between 0-.347 volt, but the system goes into open loop in about 15 seconds. Verify ground connections are clean and tight at terminals D6 and D7. An open circuit in these terminals result in a Code 13. If code is intermittent, see TESTS W/O CODES article.

Fig 1: Code 13 Circuit Diagram
G90E15820
Fig 2: Code 13 Flow Chart 1 of 2
G90F15821
Fig 3: Code 13 Flow Chart 2 of 2
G90G15822