why is my "service engine soon" light still on after problem was fixed on 2004 Cadillac DeVille

check gas cap and service engine soon light was on, smoke test confirmed leak from vent selenoid. had it replaced, but service engine soon light came back on. did another smoke test and checked codes and the codes the mechanic got back says its the vent selenoid but mechanic says its working properly

by in Victoria, TX on April 12, 2012
1 answer 1 comment
ANSWER by on April 12, 2012
NO ITS NOT ,TRY ANOTHER MECH ITS GOT TO BE ANOTHER ISSUE IN THAT CICUIT.THE SMOKE TEST ONLY SHOWS VAC LEAKS NOT MALFUNCTIONS
COMMENT by on April 17, 2012
very helpful info, i really appreciate it! finally something to go on!