DTC P0171: Fuel Trim Too Lean: Condition

DTC is set when short term or long term fuel trim values do not meet specified value while PCM adaptive memory drive mode is running. See DRIVE MODES  under SELF-DIAGNOSTIC SYSTEM. This is a continuous monitor. MIL is illuminated when Powertrain Control Module (PCM) detects malfunction during 2 consecutive drive cycles. Possible causes are:

• Misfire.
• Front HO2S malfunction.
• Fuel pressure regulator malfunction.
• Fuel pump malfunction.
• Fuel filter plugged.
• Fuel lines or fuel pump leaking.
• Exhaust system leak.
• Purge solenoid valve malfunction.
• Purge solenoid hoses improperly connected.
• Low compression.