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Home › Infiniti › 1997 › QX4 › Repair and Diagnosis › Engine Performance › System › Engine Controls - Tests W/Codes 3.3 › Circuit Tests › DTC P0171: Fuel Injection System Function - Right Bank (Lean Side)

DTC P0171: Fuel Injection System Function - Right Bank (Lean Side)

  1. Check Exhaust/Intake Air Leak  - Start engine and run at idle. Listen for exhaust air leaks before three way catalyst. Listen for intake air leaks after MAF sensor. If any leaks are detected, repair or replace appropriate parts or systems as required. If no leaks are detected, go to next step.
  2. Check Input Signal Circuit  - Turn ignition off. Disconnect front HO2S harness connector and ECM harness connector. See Figure and Figure . Using an ohmmeter, check continuity as follows: See Figure and Figure .
    • Between ECM harness connector terminal No. 46 (White wire) and front HO2S harness connector terminal No. 2 (White wire). Continuity should exists.
    • Between ECM harness connector terminal No. 46 and ground. Also, between front HO2S harness connector terminal No. 2 and ground. Continuity should not exist.

    If continuity is as specified, go to next step. If continuity is not as specified, repair fault in White wire or connector.

  3. Check Fuel Pressure  - Turn ignition off. Relieve fuel pressure. See REMOVE/INSTALL/OVERHAUL article. Install fuel pressure gauge. With ignition on, fuel pressure should be about 43 psi (3.0 kg/cm2 ). At idle, fuel pressure should be about 34 psi (2.4 kg/cm2 ). If fuel pressure is not as specified, check for fault in fuel pump and related circuitry. If fuel pressure is okay, inspect MAF sensor. See DTC P0100: MASS AIRFLOW SENSOR.
  4. Check Function Of Injectors  - Install all removed parts and reconnect all connectors. Start engine and listen for clicking sound from each injector. If any injectors fail to operate, see SYSTEM/COMPONENT TESTS article. If all injectors function properly, allow engine to cool down and go to next step.
  5. Turn ignition off. Remove injector assembly, keeping fuel hose and all injectors connected to injector gallery. Disconnect ignition coil harness connector. Crank engine for about 3 seconds. Verify fuel sprays from each injector. If any injector fails to spray fuel, replace faulty injector. If all injectors spray fuel, go to next step.
  6. Check ECM pins and terminals for damage or corrosion. Check condition of ECM harness connector. Reconnect ECM harness connector and retest.
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