I kept getting a CEL in the Durango, so I took it to my friends shop to have him check the code(s). He found a P0456, which is a code on the evaporative emissions system. He said that most of the time when they see the code with a vehicle the age and miles of my Durago, it's the flapper on the capless filler that's leaking. I didn't know this, but my Durango and many other vehicles have a pump that slightly pressurizes the fuel tank and monitors if there is a leak-down. If a leak, even small, is detected, you'll get a CEL light and usually a P0456. He attempted to clean the door, reset the code, because we wanted to see of the code would come back. Sure enough, it did so we replaced the capless filler neck. It was on back order for a few weeks, but it did get replaced, which fixed the CEL. We also preemptively replaced the pump, at a cost of $60, so we didn't have the labor of removing the inner fender again. The entire job was $660 and I only got charged an hour of labor. The mechanic that did the job has 35 years of experience and really hustles. He'll do three jobs in the time it takes another mechanic there to do one. Both experienced and do good work, just one of the guys does everything in low gear.
I had no idea how complex a filler neck is, nor did I know they would have to replace the entire assembly all the way to the tank.
I had no idea how complex a filler neck is, nor did I know they would have to replace the entire assembly all the way to the tank.