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Home >> Infiniti >> 1999 >> Q45 Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - Introduction >> Additional System Features >> Fuel Feedback Monitoring Using Mil
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Fuel Feedback Monitoring Using Mil

  1. Enter Mode II diagnostics using MIL. See RETRIEVING CODES USING MIL  under SELF-DIAGNOSTIC SYSTEM. If engine is started at this stage, MIL will display condition of air/fuel mixture, monitored by the front Heated Oxygen Sensors (HO2S), whether the vehicle is in closed loop or open loop. With engine at normal operating temperature, run engine at about 2000 RPM for 2 minutes under no-load condition. MIL should flash 5 times every 10 seconds indicating normal operating condition of air/fuel mixture monitored by front HO2S(s).
  2. When MIL is on, it indicates a lean condition. When MIL is off, it indicates a rich condition. MIL switching on and off indicates closed loop operation. If MIL remains on or off, it indicates an open loop condition.
  3. To switch to opposing HO2S, turn diagnostic test mode selector on PCM fully clockwise, wait 2 seconds and turn mode selector fully counterclockwise. MIL will now indicate changing to opposing HO2S by rapidly flashing and returning to lean/rich cycling. HO2S feedback of the opposing bank HO2S will now be displayed by MIL.
  4. Repeat step  3 to switch back to original HO2S feedback signal. Switch from bank to bank as necessary. To erase stored DTC information, go to ERASING STORED INFORMATION  under SELF-DIAGNOSTIC SYSTEM. To remain in Mode II, turn engine off and immediately turn ignition on.
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