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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 38 (Engine Controls - Self-Diagnostics) >> Diagnostic Tests >> DTC P0171: Fuel Injection System Too Lean - Bank 1, DTC P0172: Fuel Injection System Too Rich - Bank 1, DTC P0174: Fuel Injection System Too Lean - Bank 2 &/Or DTC P0175: Fuel Injection System Too Rich - Bank 2 >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Maxima and 2002 Infiniti I35. 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 after MAF sensor. 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 . Disconnect appropriate HO2S1 harness connector. See Figure . On bank 1, check continuity of White wire between HO2S1 harness connector terminal No. 1 and ECM harness connector terminal No. 91. See Figure . On bank 2, check continuity of White wire between HO2S1 harness connector terminal No. 1 and ECM harness connector terminal No. 92. 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 51 psi (350 kPa) at idle. If fuel pressure is okay, go to next step. If fuel pressure is not okay, repair fuel system as necessary.
    4. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  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 2.0-6.0 g/sec at idle and 7.0-20.0 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 P0102: MASS AIRFLOW SENSOR CIRCUIT LOW INPUT OR DTC P0103: MASS AIRFLOW SENSOR CIRCUIT HIGH INPUT  .
  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 on bank 2 (for DTC P0171 or DTC P0172) or bank 1 (for DTC P0174 or DTC P0175). 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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