P0171

[PO171] The scan tool indicates Diagnostic Trouble Code (DTC) PO171: The fuel system is too lean.

NOTE: If some of the DTCs listed below are stored at the same time as DTC PO171 or P0172, troubleshoot those DTCs first, then troubleshoot DTC P0171 or P0172.



PO1O6-8: MAP Sensor
P0135: Primary HO2S Heater (Sensor 1)
P0136: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S Heater (Sensor 2)
PO4O1: EGR Flow Insufficient
PO441: EVAP System Incorrect Purge Flow
P1491: EGR Valve Lift Insufficient
P1498: EGR Valve Lift Sensor High Voltage

Possible Cause:

[DTC P0171: System too lean]
^ Fuel Pump: not enough flow/pressure
^ Fuel Feed Line: clogged, leaking
^ Fuel Pressure Regulator: stuck open
^ Fuel Filter: clogged
^ Fuel Injector: clogged, air inclusion
^ Gasoline: doesn't meet Owner's Manual spec.
^ Primary HO2S (Sensor 1): deteriorated
^ MAP Sensor: wrong characteristics
^ EGR System: not enough flow
^ Valve Clearance: too tight
^ Exhaust Lines: leaking