snorkel

[Boxtaboy]

I know folks who have taken out and then reinserted snorkels before, so I'm pretty sure you can reinsert, but it may be true that it's easy to break off a portion of the airbox while removing the snorkel if not careful. Taking out the snorkel and having an RMS shouldn't produce a CEL. Did you run your car through a car wash or spray water through the intake while washing your car one day?

Maybe it's something unrelated, like leaving the gas cap unsecured after filling up one day.