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Home >> Acura >> 2003 >> 3.5RL >> Repair and Diagnosis >> Engine Performance >> System >> Engine Performance System Self-Diagnostics >> Diagnostic Tests >> DTC P0171: Fuel System Too Lean (Right Bank - Bank 1); DTC P0172: Fuel System Too Rich (Right Bank - Bank 1); DTC P0174: Fuel System Too Lean (Left Bank - Bank 2) Or DTC P0175: Fuel System Too Rich (Left Bank - Bank 2) (2004 3.5RL) >> Diagnostic Procedure

Diagnostic Procedure

  1. Check fuel pressure. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is okay, go to next step. If fuel pressure is too high, check fuel pressure regulator and fuel return pipe. Repair as necessary. If fuel pressure is too low, check fuel pump, fuel feed pipe, fuel filter and fuel pressure regulator. Repair as necessary.
  2. Start engine. Hold engine speed at 3000 RPM with no load and transmission in Park or Neutral until radiator fan comes on. Using HDS (Honda Diagnostic System) or scan tool, check right primary HO2S output voltage for DTC P0171 or DTC P0172, and check left primary HO2S output voltage for DTC P0174 or DTC P0175. If output voltage stays at less than 0.3 volt or more than 0.6 volt, replace suspect primary HO2S. If output voltage does not stay at less than 0.3 volt or more than 0.6 volt, go to next step.
  3. Using a vacuum pump, apply vacuum to intake manifold side of EVAP canister purge valve. If EVAP canister purge valve holds vacuum, check EGR system. If EGR system is okay, replace fuel injectors. If EVAP canister purge valve does not hold vacuum, replace EVAP canister purge valve.
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