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Home >> Infiniti >> 2003 >> Q45 >> Repair and Diagnosis >> External Pages >> Different car >> Section 201 (Engine Control System) >> DTC P1148, P1168: Closed Loop Control >> Overall Function Check >> With GST
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With GST

WARNING: This page is about a different car, the 2004 Infiniti Q45. However, it is still accessible from the selected car via links, so may be relevant.
  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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