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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 204 (Engine Controls - Self-Diagnostics - 1.8L - Ca) >> Diagnostic Tests >> DTC P0171 Or P0172: Fuel Injection System Function >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.
  1. Start engine and let it idle. Check for leaks in exhaust system before 3-way catalyst. Check intake system for leaks. If problem exists, repair or replace faulty components as necessary and retest system. If problem does not exist, go to next step.
  2. Turn ignition off. Disconnect front A/F sensor harness connector and PCM harness connector. See Figure and Figure through Figure . Check harness continuity between ECM terminals and A/F sensor 1 terminals as shown in ECM TO A/F SENSOR (SENSOR 1) CONNECTOR TERMINAL NO.S  table. See Figure and Fig 1 . Continuity should exist. Also check circuit for short to ground and short to voltage. If problem exists, repair as necessary and retest system. If problem does not exist, go to next step.
    ECM TO A/F SENSOR (SENSOR 1) CONNECTOR TERMINAL NO.S

    ECM Terminal No. Wire Color A/F Sensor Terminal No.
    62 White/Blue 2
    63 White 5
    64 Orange/Blue 1
    65 Orange 6
  3. Reconnect all harness connectors. Check fuel pressure. See BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure should be 51 psi (3.57 kg/cm2 ) at idle. If fuel pressure is not as specified, repair fuel system as necessary. If fuel pressure is as specified, go to next step.
  4. Start engine and let it idle. Using scan tool, check MAF sensor signal. At idle, value should be 1.4-4.0 gm/sec. At 2500 RPM, value should be 5.4-10.0 gm/sec. If values are as specified, go to next step. If values are not as specified, repair MAF sensor or circuit. See DTC P0101, DTC P0102, DTC P0103 OR DTC P1102: MASS AIRFLOW (MAF) SENSOR  .
  5. With engine idling, listen to each injector for clicking noise. If any injector does not click, repair circuit or replace injector as necessary. See SYSTEM & COMPONENT TESTING article. If all injectors click, go to next step.
    6. NOTE: NEW "O" rings must be used on all fuel injectors once removed.
  6. Turn ignition off and allow engine to cool. Ensure no fire hazards exist and remove fuel injector assembly with fuel lines and harness connectors connected. Place a suitable cup under each fuel injector to collect fuel. Disconnect all ignition coil harness connectors. Turn ignition on. Verify fuel is not dripping from fuel injectors. Replace fuel injectors which are leaking. Crank engine for 3 seconds and ensure each fuel injector sprays fuel. If problem does not exist, go to next step. If problem exists, repair as necessary and retest system.
  7. No problem is indicated at this time. Problem may be intermittent. See TESTING PROCEDURE  .
Fig 1: Fuel Injector Circuit Wiring Diagram
G00274266Courtesy of NISSAN MOTOR CO., U.S.A.
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