Possible Cause

P0171 

• Intake air leakage
• A/F sensor 1
• Fuel injector
• Exhaust gas leakage
• Incorrect fuel pressure
• Lack of fuel
• Mass air flow sensor
• Incorrect PCV hose connection

P0174 

• Intake air leakage
• A/F sensor 1
• Fuel injector
• Exhaust gas leakage
• Incorrect fuel pressure
• Lack of fuel
• Mass air flow sensor
• Incorrect PCV hose connection