P0171 Honda -

Question

we only rec. the code of P0171 but the car is very loud now. it was not loud like this yesterday. The car just passed smog on 10/20/14. WTH.. this is a honda si 2003. please help

Answer 1

P0171 Fuel trim too lean

Lean fuel trim lean  is where there is more air than fuel , some  common causes of lean fule trim are vacuum leaks, vacuum leak are some of the main cause for lean fuel trim condition. check for any vacuum hose that have gotten disconnected or ruptured.