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Home › Infiniti › 2004 › FX35 AWD › Repair and Diagnosis › Engine Performance › Engine Control System › DTC P1276 & P1286 A/F Sensor 1 › Diagnostic Procedure

Diagnostic Procedure

  1. Check Ground Connections 
    1. Turn ignition switch OFF.
    2. Loosen and retighten three ground screws on the body. See Figure. Refer to GROUND INSPECTION .

      OK or NG

      1. OK: Go to 2.
      2. NG: Repair or replace ground connections.

  2. Check Air Fuel Ratio (A/F) Sensor 1 Power Supply Circuit 
    1. Disconnect air fuel ratio (A/F) sensor 1 harness connector. See Figure.
    2. Turn ignition switch ON.
    3. Check voltage between air fuel ratio (A/F) sensor 1 terminal 3 and ground with CONSULT-II or tester. See Figure.
      1. Voltage: Battery voltage 

      OK or NG

      1. OK: Go to 4.
      2. NG: Go to 3.

  3. Detect Malfunctioning Part 

    Check the following.

    • Harness connectors E18, F48
    • Fuse block (J/B) connector E201
    • 10A fuse
    • Harness for open or short between air fuel ratio (A/F) sensor 1 and fuse
      1. Repair or replace harness or connectors.

  4. Check Air Fuel Ratio (A/F) Sensor 1 Input Signal Circuit 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between the following terminals. See Figure.

      Refer to wiring diagram. See WIRING DIAGRAM .

      1. Continuity should exist  .
    4. Check harness continuity between the following terminals and ground. See Figure.

      Refer to wiring diagram. See WIRING DIAGRAM .

      1. Continuity should not exist  .
    5. Also check harness for short to ground and short to power.

      OK or NG

      1. OK: Go to 5.
      2. NG: Repair open circuit or short to ground or short to power in harness or connectors.

  5. Check Intermittent Incident 

    Perform TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

    OK or NG

    1. OK: Go to 6.
    2. NG: Repair or replace.

    6. CAUTION:
    • Discard any air fuel ratio (A/F) sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard surface such as a concrete floor; use a new one.
    • Before installing new air fuel ratio (A/F) sensor, clean exhaust system threads using Heated Oxygen Sensor Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.
  6. Replace Air Fuel Ratio (A/F) Sensor 1 

    Replace air fuel ratio (A/F) sensor 1.

  7. Inspection end 
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