Help I need to pass smog

Question

What I have are PO455 , PO171 & PO174. Where should I start? Would it be with the O2 senors it has 4. 2 upper and 2 lower. It's a California car and with the check engine light on you can't pass a smog check.

Answer 1

P0455 Evap control system leak

P0171 Fuel trim lean Bank 1

P0174 Fuel trim lean Bank 2

With P0174 and P0171 this is a lean condition lean condition are mostly caused vacuum leaks which are leaks that get past the MAF (mass air flow) these are unmetered and upset the air to fuel ratio. and this is what your engine has P0455 means there is no purge flow this can happen when the vacuum hose to the purge valve is disconnected or has a leak, which can a does cause a lean bank system Check the purge valve you might be able to hear the vacuum leak. and make the repair there.Use the underhood stick for the location of the purge valve