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Home >> Infiniti >> 1991 >> G20 Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Fuel System >> Fuel Control >> Feedback System
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Feedback System

  1. Start engine and warm to operating temperature. Ensure idle speed and timing are adjusted to specification. Increase engine speed to about 2000 RPM for 2 minutes under no-load condition. Using a small screwdriver, turn diagnostic mode selector screw on ECU.
  2. With screwdriver turned fully clockwise for at least 2 seconds, inspection lights will begin to flash. Turn screwdriver fully counterclockwise. This switches ECU to Mode II which is used to monitor exhaust gas sensor feedback signals.
  3. With engine speed at 2000 RPM for 2 minutes, LED should flash at least 5 times during a 10-second period. If sensor does not respond as indicated and no other faults which may affect air/fuel mixture are indicated by ECU self-diagnostic system, use a voltmeter to verify input signals to ECU are correct. If so, replace oxygen sensor. If still not correct, replace ECU.
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