Circuit/System Verification: P0171

WARNING: This page is about a different variant/trim than selected.

NOTE: EVAP purge enablement may cause the FT to be momentarily outside the normal range.

Allow the engine to reach operating temperature. With the engine running, observe the Long Term FT parameter with a scan tool. The reading should be between 0-20 percent.

If greater than the specified range, inspect for the following:

Vacuum hoses for splits, kinks, and improper connections
Insufficient fuel in the tank
Low fuel pressure-Refer to Fuel System Diagnosis .
Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
Malfunctioning fuel injectors-Refer to Fuel Injector Diagnosis (J39021 or Tech 2) or Fuel Injector Diagnosis (CH47976) .
Missing, loose, or leaking exhaust components from the HO2S forward-Refer to Symptoms - Engine Exhaust .
Vacuum leaks at the intake manifold, the throttle body, and the injector O-rings
The air induction system and the air intake ducts for leaks or for a missing air filter element
A cracked EVAP canister
Evaporative pipes obstructed or leaking
The crankcase ventilation system for leaks-Refer to Crankcase Ventilation System Inspection/Diagnosis .
The HO2S for improper installation and for electrical wires or connectors that may have contacted the exhaust system
The HO2S signal circuit open, shorted to ground, or shorted to the low reference circuit
Malfunctioning engine components-Refer to Symptoms - Engine Mechanical .