I just got my first CEL last week (during that cold spell) and the dealer said it was due to a bad purge valve. They quoted $230 to change it.
Here's the thing: I'm returning the car next month (lease is up) and really don't want to spend the money to repair it. PLUS, I got the WearCare protection coverage, so I can just return it and let WearCare cover the repair.
So, how bad is it for my car to keep driving with a bad purge valve? The CEL went off by itself and has stayed off. The only thing different about the drive is a slightly rough idle.