DTC P0171, P0174: Notes

• P0171 indicates that the fuel/air ratio is too lean (RH).
• P0174 indicates that the fuel/air ratio is too lean (LH).
• The adaptive fuel strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit.

• 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
• Purge solenoid valve is leaking when the canister is clean
• Fuel supply line restricted
• Fuel rail pressure sensor bias

Exhaust System:

• Exhaust leaks in the exhaust manifold gasket or mating gaskets before or near the HO2S

Intake Air System:

• Air leaks after the MAF sensor
• Vacuum leaks
• PCV system is leaking or the valve is stuck open
• Improperly seated engine oil dipstick
• Damaged or contaminated MAF sensor