I just change the gas cap and I still getting the same code what do i need to check next and where?

 

Old post, but I'm getting the same code after replacing the gas cap. Before the gas cap replacement, I was getting P0456.

 

Hi
Need to know the year of the van, could be cracked hoses, LDP pump, vent valve, NVLD pump or ESIM valve.

 

Every once in awhile I get code P0456 and P1684 together, even though the battery hasn't been disconnected for months. Happened once last year this time and twice so far this month.

I disconnect the battery for few minutes (say 10 minutes) to get code P0456 to go away. The P1684 code will stay for the next 50 restarts, of course.

Apparently, some sort of glitch in my case. Only thing I have noticed is that it's only occuring during this time of year and when it's cool and damp. May not show up again until next year this time.