I had a check engine light throw with code P0455 (large leak). I ordered a new vent solenoid because I had this same issue in my wife's Escalade. When I crawled under there to install it, the clip on the hose was broken and it was completely disconnected. It must've rattled loose over time. I fixed it with electrical tape for now and ordered the hose. I installed the new vent solenoid anyway and sanded/painted the bracket while I was at it because it was rusted to hell. Just a reminder to always start with the easiest solution! Sometimes you get lucky. Just sharing to archive for anyone else who gets the code.

 

More info: it's located under the rear drivers side


Broken clip on hose caused it to get completely disconnected

 

Electrical tape wont last long under the elements. Better way to hold permanently:

 

good call I do have those exact zip ties. I already ordered the hose so I'm just going to replace it

 

It is possible to "plastic weld" a broken clip to repair it.

Also have to add that it turned out to be the fpm.