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Home >> Ford >> 2005 >> Escape Base, 3.0 1, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 35 (Engine Controls - Powertrain DTC Charts And Description - (Hybrid)) >> Diagnostic Trouble Code (DTC) Charts and Descriptions >> DTC P0171: System Too Lean (Bank 1)

DTC P0171: System Too Lean (Bank 1)

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P0171 - SYSTEM TOO LEAN (BANK 1)

Description:  The adaptive fuel strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Refer to FUEL TRIM for more information.
Possible Causes:  Air Measurement System.
  • Mass air flow (MAF) sensor.

Fuel System.

  • Fuel pressure regulator (leaking, faulty).
  • Fuel filter plugged, dirty.
  • Fuel pump (weak, check valve leaking).
  • Leaking/contaminated fuel injectors.
  • Low fuel pressure or running out of fuel.
  • EVAP canister purge valve leaking (when canister is clean).
  • Fuel supply line restricted.
  • Fuel rail pressure sensor (incorrect reading).

Air Induction System.

  • Air leaks after the MAF sensor.
  • Vacuum leaks.
  • PCV system (leak or valve stuck open).
  • Improperly seated engine oil dipstick.

Exhaust System.

  • Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets).

EGR system.

  • EGR valve tube/gasket leak.
  • EVR solenoid vacuum leak.
Diagnostic Aids:  View freeze frame data to determine the operating conditions when the DTC was set. Aids: Observe the LONGFT1 PID. Refer to ADAPTIVE FUEL DIAGNOSTIC TROUBLE CODE (DTCS) DIAGNOSTIC TECHNIQUES for more information.
Application  Key On Engine Off  Key On Engine Running  Continuous Memory 
All - - GO to Pinpoint Test H .