Check engine light on with code P0410

I had a check engine light while driving. The scan shows code P0410-Secondary air injection: (fault function chain)Air flow is too low.
I checked all the relays, fuses, vacuum lines.
Replaced the post catalytic o2 sensor.
Erased the code and returned on driving 2 miles.
I notice smell of gasoline on and off in the car and rough idle as well.
Planning on changing the canister purge valve.
Sir, waiting for your expert comments.