2002 Chrysler Concorde code P0441 emmision control system

I took my 2002 chrysler concorde to auto zone because the check engine light was on and the code came back as p0441. They said the purgeflow in the evaporative emmision control system is incorrect. What should I do I already changed the fuel cap like they said but my check engine light is still on now the garage wants me to pay 90 dollars for a full diagnostic check is it worth doing and how bad is this problem if it was to go on without fix?