I have a 2001 Sierra and have never had problems before. It recently started giving check engine codes. My mechanic said a friend of his that works at a gm dealership told him it was do to condensation under the dash. He is trying to dry it out and get the codes reset. It started just all of a sudden. The vehicle is kept inside an enclosed garage all the time except when I use it to pull my boat on the weekends. He showed me under the dash where the computer is and the metal cover in there is spotted with rust all over the place. Has anyone else seen this? Has there ever been a recall by GM?