P0171 Honda civic-

Question

2009 Honda Civic Si check engine code P0171
System too lean... What can cause this out of the blue?

Answer 1

Lean means there is too much air, check for intake leaks is the first thing to do.

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