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Home >> Infiniti >> 2001 >> G20 Base, Automatic, RE4F03W >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0171 Or P0172: Fuel Injection System Function >> Procedure

DTC P0171 Or P0172: Fuel Injection System Function: Procedure

  1. Start engine and let it idle. Check for leaks in exhaust system before 3-way catalyst. Check for leaks in intake system after MAF sensor. Repair leaks as necessary and retest system. If no leaks are detected, go to next step.
  2. Turn ignition off. Disconnect front HO2S harness connector and ECM harness connector. See Figure. Check continuity of White wire between ECM harness connector terminal No. 62 and front HO2S harness connector terminal No. 2. See Figure. Also check circuit for short to ground and short to voltage. Repair circuit as necessary and retest system. If circuit is okay, go to next step.
  3. Check fuel pressure. See BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is okay, go to next step. If fuel pressure is not okay, check fuel pump, fuel pressure regulator and fuel lines. See FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. Repair as necessary and retest system.
  4. Install all removed parts. Start engine and warm to normal operating temperature. Select MODE 1 with scan tool, and read Mass Airflow (MAF) signal. MAF reading should be 2.5-5.0 g/sec at idle and 7.1-12.5 g/sec at 2500 RPM. If MAF reading is as specified, go to next step. If MAF reading is not as specified, repair MAF sensor or circuit. See DTC P0100: MASS AIRFLOW (MAF) SENSOR .
  5. With engine operating at idle speed, listen to each injector for clicking noise. If any injector does not click, repair circuit or replace injector. See FUEL SYSTEM in SYSTEM & COMPONENT TESTING article. If all injectors click, go to next step.
  6. Turn ignition off and allow engine to cool. Ensure no fire hazards exist and remove injector assembly with fuel lines and harness connectors connected. Place a suitable cup under each injector to collect fuel. Disconnect all ignition coil harness connectors. Turn ignition on. Verify fuel is not dripping from injectors. Replace injectors which are leaking. Crank engine for 3 seconds and ensure each injector sprays fuel. Replace injectors that do not spray fuel. If all injectors are okay, go to next step.
  7. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
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