I'd lean towards preposterous. Sorry.

Sorry Dan, that won't set a CEL.

I can't believe I haven't mentioned the obvious. Have you put fuel in the tank recently?

The Evaporative emission system will use manifold vacuum to empty gasoline vapors out of the fuel tank to burn off before they can polute. It has to maintain this vacuum for a specific time. This vacuum actually has a sensor, and if it fails the test, it will set a CEL. The most common cause for a CEL? A loose gas cap!

I checked the loose gas cap - not an issue, unfortunately. I'd be happy if it was just something that simple.