when does the ecm command the pruge valve open and vent valve to close 1999 pathfinder code p1448

Question

check eng lite on purge vent and fuel tank pressure sensors all have power with key on, also all three valves clicks during bench test also the three valves hold vacuum thank you

Answer 1

Check the charcoal canister a lot of times it comes apart   internally and send it pellets all the purge valve and plugs it up.