2014 Fiat 500L - P0456

[ethomas]

2014 Fiat 500L Easy; Current miles: 66127

About 1000 miles ago, the car threw a P0456. It came on at engine start up, or rather it didn't turn off after the start up sequence.
It was days after filling gas, so couldn't have been the gas cap. I still checked the gas cap; opened and closed it. Didn't help.
Tried to clear the code using an OBDII device; but wouldn't clear.
Then, after around 200 miles, immediately after filling gas, when I started the car, the light was gone - just like that.
Almost seemed like the filling fixed it. Or, could it be that the gas cap seated well this time?

Today, it threw the code again. Just like last time, it came on at engine start up, days after filling gas.
Tried to clear the code; Didn't work.
About 10 miles later, I filled gas to see if it would go off like the previous time. It didn't.

What could be the issue?
Could it actually be the gas cap? I have a capless gas tank (which I hate and don't trust). Is there a way to convert that to a normal gas cap?
I believe it could be the purge valve or charcoal canister. Is there a way to test? Anyone has this happen to you?

I am kind of confused by the way it turned off by itself immediately after filling gas. Any thoughts?

Thank you for any help.

[5port]

If you have a capless gas tank it may be time for a cleaning. That would explain the code coming in an intermittent fashion. My 500X had the same issue recently and cleaning the capless device cured it.

[ethomas]

Following the video, I cleaned the capless fuel filler a week ago, but the CEL still is on 300 miles and a week later.
My quest for a solution is on ....

Today, I disconnected the negative terminal of the battery for about half an hour and on reconnecting, the CEL didn't come back. I know it is not a fix, but want to see how long it takes for it to come back. I will update here.