WARP211

I've been throwing a code P0410 I check the Air Pump it comes on and I'm getting air suck in and blowing out all the way to the check valves. My question is does the check valves post to prevent exhaust fumes from coming out?? I had the valves bolted on the exhaust with the tubing off and exhaust was coming out does that mean the valves are bad?? Are they suppose to only let the A.I.R system blow air thru them and not let exhaust come in??