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 toPOWERTRAIN CONTROL SOFTWARE Fuel Trim for more information.
Possible Causes:	Fuel System: Damaged or leaking fuel pulse damper Fuel filter plugged or dirty Damaged or worn fuel pump Leaking fuel pump check valve Leaking/contaminated fuel injectors Low fuel pressure or running out of fuel Evaporative emission (EVAP) canister purge valve is leaking when the canister is clean Fuel supply line restricted Fuel rail pressure sensor bias Ethanol content in the fuel Exhaust System: Exhaust leaks in the exhaust manifold gasket or mating gaskets before or near the heated oxygen sensor (HO2S) EGR System: Vacuum hose disconnected on exhaust gas recirculation (EGR) system module (ESM) applications EGR valve tube/gasket leak EGR vacuum regulator solenoid leak Intake Air System: Air leaks after the mass air flow (MAF) sensor Vacuum leaks Positive crankcase ventilation (PCV) system is leaking or the valve is stuck open Incorrectly seated engine oil dipstick Intake air turbulence due to incorrect air filter Damaged or contaminated MAF sensor
Diagnostic Aids:	View the Freeze Frame Data to determine the operating conditions when the DTC was set. Observe the LONGFT1 and LONGFT2 PIDs. Refer toADAPTIVE FUEL DTC DIAGNOSTIC TECHNIQUES for more information and the appropriate pinpoint test for specific concern identification.
Application		Key On Engine Off	Key On Engine Running	Continuous Memory
All		-	-	refer to PINPOINT TEST H .