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Home >> Infiniti >> 2004 >> Q45 >> 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. Set voltmeter probes between ECM terminal 114 [HO2S1 (B1) signal] or 115 [HO2S1 (B2) signal] and ground. See Figure.
  3. Check the following with engine speed held at 2,000 RPM constant under no-load.
    • The voltage should go above 0.70V at least once.
    • The voltage should go below 0.21V at least once.
  4. If NG, go to Diagnostic Procedure  .
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