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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 69 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0171: Fuel Injection System Too Lean - Bank 1, DTC P0172: Fuel Injection System Too Lean - Bank 2, DTC P0174: Fuel Injection System Too Rich - Bank 1 Or DTC P0175: Fuel Injection System Too Rich - Bank 2 >> Diagnostic Procedure (2.4L)

Diagnostic Procedure (2.4L)

WARNING: This page is about a different car, the 2002 Nissan Xterra and 2002 Nissan Frontier. However, it is still accessible from the selected car via links, so may be relevant.
  1. Start engine and let it idle. Check for exhaust air leaks before 3-way catalyst. Check for intake air leaks between MAF sensor and intake manifold. If any leaks are found, repair as necessary. If no leaks are found, go to next step.
  2. Turn ignition off. Disconnect ECM harness connector. See Figure or Figure . Disconnect HO2S1 harness connector. See Figure . Check continuity of Black wire between HO2S1 harness connector terminal No. 2 and ECM harness connector terminal No. 50. See Figure . Also, check circuit for short to ground and short to voltage. If problem is found, repair as necessary. If problem is not found, go to next step.
  3. Check fuel pressure. See BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure should be about 34 psi (235 kPa) with fuel pressure regulator vacuum hose connected and about 43 psi (294 kPa) with fuel pressure regulator vacuum hose disconnected. If fuel pressure is okay, go to next step. If fuel pressure is not okay, repair fuel system as necessary.
  4. Install all removed parts. Start engine and warm to normal operating temperature. Using CONSULT-II, select MASS AIR FLOW in DATA MONITOR mode. Using generic scan tool, select MODE 1, and read mass airflow. MAF reading should be 0.9-5.8 g/sec at idle and 7.5-13.2 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 P0101, DTC 0102 OR DTC P0103: MASS AIRFLOW SENSOR  .
  5. Allow engine to idle. Using CONSULT-II, perform POWER BALANCE in ACTIVE TEST mode. Each circuit should produce a momentary engine speed drop. If not using CONSULT-II, listen to each fuel injector. Clicking noise should be heard from each injector. If operation is as specified, go to next step. If operation is not as specified, diagnose and repair fuel injector circuits. See FUEL SYSTEM in SYSTEM & COMPONENT TESTING article.
  6. Turn ignition off. Allow engine to cool and ensure no fire hazards exist. Remove injector assembly, keeping fuel hose and all injectors connected to injector gallery. Place a suitable cup under each injector to collect fuel. Disconnect injector harness connectors. Disconnect all ignition coil harness connectors. Turn ignition on. Ensure fuel does not drip from any injector. If fuel drips from any injector, replace injector from which fuel is dripping. Crank engine for 3 seconds. Ensure each injector sprays fuel. Replace any injector from which fuel does not spray. 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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