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Home >> Infiniti >> 2003 >> FX35 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1148: Closed Loop Control Function (Bank 1) & DTC P1168: Closed Loop Control Function (Bank 2) >> Overall Function Check (Using GST)
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Overall Function Check (Using GST)

NOTE: Use this procedure to check the overall function of the heated oxygen sensor 2 circuit. During this check, a DTC might not be confirmed.
  1. Start engine and warm it to normal operating temperature.
  2. Place voltmeter probes between ECM terminal No. 35 (HO2S1 B1 signal), or No. 16 (HO2S1 B2 signal) and engine ground. See Fig 2.
  3. Check the following with engine speed held at a constant 2000 RPM under no load.
    • The voltage should go above 0.70 volt at least once.
    • The voltage should go below 0.21 volt at least once.
  4. If NG is displayed, go to DIAGNOSTIC PROCEDURE . If NG is not displayed, system is okay at this time.
Fig 1: Identifying DTCs P1148 & P1168 Confirmation Procedure Testing Conditions
G00271778Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Testing HO2S1 B1 & B2 Voltage
G00271779Courtesy of NISSAN MOTOR CO., U.S.A.
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