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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 112 (Engine Controls Self-Diagnostics - Pathfinder) >> Diagnostic Tests >> DTC P0171: Bank 1 Fuel Injection System Too Lean Or DTC P0174: Bank 2 Fuel Injection System Too Lean >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Nissan Pathfinder. 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 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 116-pin harness connector. ECM is located behind instrument panel lower cover. See Figure. Disconnect appropriate HO2S 1 harness connector. See Figure or Figure . On bank 1, check continuity of Green wire between HO2S 1 harness connector terminal No. 1 and ECM harness connector terminal No. 35. See Figure and Figure . On bank 2, check continuity of Green/Black wire between HO2S 1 harness connector terminal No. 1 and ECM harness connector terminal No. 16. Also, check circuits for short to ground or short to voltage. If problem is found, repair as necessary. If no problem is found, go to next step.
  3. Check fuel pressure. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is okay, go to next step. If fuel pressure is not okay, repair fuel system as necessary. See FUEL SYSTEM in SYSTEM & COMPONENT TESTING article.
    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 AIRFLOW in DATA MONITOR mode. Using generic scan tool, select MODE 1, and read MASS AIRFLOW parameter. 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 OR P0103 .
  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 fuel injector assembly, keeping fuel hose and all injectors connected to injector gallery. See FUEL SYSTEM in REMOVAL & INSTALLATION - PATHFINDER article. Place a suitable cup under each injector to collect fuel. 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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