What causes a P0171 code in a 1998 Jeep Grand Cherokee Laredo with a 4.0 L engine?

Question

My Grand Cherokee started running rough at idle and the Check Engine Light came on. The Diagnostic Code P0171 was displayed on the meter. The handbook described it as
System too Lean (Bank 1). What is the cause and how do I fix it?

Answer 1

too lean means there is too much air, check for intake leaks and clean the mass air flow sensor with mass air flow sensor cleaner.

Possible causes

- Intake air leaks

- Faulty front heated oxygen sensor

- Ignition misfiring

- Faulty fuel injectors

- Exhaust gas leaks

- Incorrect fuel pressure

- Lack of fuel

- Faulty Mass Air Flow (MAF) sensor

- Incorrect Positive Crankcase Ventilation (PCV) hose connection