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Home >> Infiniti >> 2004 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System >> DTC P1278, P1288: A/F Sensor 1 >> DTC Confirmation Procedure >> With GST
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With GST

  1. Start engine and warm it up to normal operating temperature.
  2. Select "MODE 1" with GST.
  3. Calculate the total value of "Short term fuel trim" and "Long term fuel trim" indications. Make sure that the total percentage should be within +/-15%.

    If OK, go to the following step.

    If NG, check the following.

    • Intake air leaks
    • Exhaust gas leaks
    • Incorrect fuel pressure
    • Lack of fuel
    • Injectors
    • Incorrect PCV hose connection
    • PCV valve
    • Mass air flow sensor
  4. Turn ignition switch OFF and wait at least 10 seconds.
  5. Start engine and keep the engine speed between 3,500 and 4,000 RPM for at least 1 minute under no load.
  6. Let engine idle for 1 minute.
  7. Increase the engine speed up to 4,000 to 5,000 RPM and keep it for 10 seconds.
  8. Fully release accelerator pedal and then let engine idle for about 1 minute.
  9. Select "MODE 7" with GST.

    If the 1st trip DTC is displayed, go to DIAGNOSTIC PROCEDURE .

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