The car has this code, syas theres a large leak in the evap emmissions system. That means I need a new gas cap right?

 

EVAP is the black canister in the engine bay on the firewall usually behind and the right on the engine. You may have not hooked up the vacuum lines correctly or one of them has a hole in it, or in one case i've seen the canister itself was broken in half (still not sure how that guy did that).