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Home >> Infiniti >> 2004 >> M45 >> Repair and Diagnosis >> Engine Performance >> Engine Control System >> DTC P1148, P1168: Closed Loop Control >> Overall Function Check >> With GST
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With GST

  1. Start engine and warm it up to normal operating temperature.
  2. Turn ignition switch OFF and wait at least 10 seconds,
  3. Start engine and keep the engine speed between 3,500 and 4,000 RPM for at least 1 minute under no load.
  4. Let engine idle for 1 minute.
  5. Set voltmeter probes between ECM terminal 114 [HO2S1 (B1) signal] or 115 [HO2S1 (B2) signal] and ground.
  6. Check the following with engine speed held at 2,000 RPM constant under no-load.
    Fig 1: Checking Voltage Between ECM Terminals & Ground
    G00796356Courtesy of NISSAN MOTOR CO., U.S.A.
    • The voltage should go above 0.70V at least once.
    • The voltage should go below 0.21V at least once.
  7. If NG, go to DIAGNOSTIC PROCEDURE .
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