How come on 2003 Buick Renduvous(11,000 miles), my service engine soon light goes on everytime I hit a puddle?

The light stays on for about 250 miles.Then it goes off again. The dealer thinks I have a leak and wants to pull the seats out and rip up the carpet. It does not make sense to me and I don,t want to pay the dealer a $1000.How come on 2003 Buick Renduvous(11,000 miles), my service engine soon light goes on everytime I hit a puddle?Sounds like water is getting splashed onto a badly made connector under the hood some place. Check out all connectors making sure they are fully closed to each other or to the components. Get something like WD40 and spray the connectors to see if this stops it. I do not think it sounds like water getting inside the passenger compartment. A good Auto Electrical guy should be able to nail this pretty quickly.