I have a 2001 Hyundai Santa Fe with the code P0455 (large EVAP leak). The gasoline filler neck pipe is routed through the wheel well and is covered with a plastic shield. The filler neck pipe rotted out due to dirt and debris being trapped between the plastic shield and the mounting bracket. I went to the dealer to purchase a new gas filler neck pipe ($95.00), and they told me that someone else with a Santa Fe had the same problem (Code P0455) with a rotted gas filler neck pipe. I replaceed the gas filler neck pipe, cleared the code and rechecked the ODB a week later, EVAP system OK now.

 

Thank you for taking the time to share this info. I'll add a little here regarding my experience with the dreaded Check Engine light.

First step was to take the truck in for diagnosis. At a cost of $130 (yes, I know) the code was cleared and a new gas cap was installed. 2 days later, light was back on. Took it back in and they were nice enough to clear the code for free. 2 days later...

Went out and bought my very own ODB reader for $70 -- standard device that connects to a standard port (for Santa Fe its behind a plastic shield located bottom left of the steering column; simply pull off the shield, port is on the right). Now I can check and clear my own codes.

Based on the post here, rather than throwing my cash into further let's-try-this diagnosis, I decided to have a look for myself. First challenge was finding out how to *safely* jack up the truck, as I had never tried this before. Me and my good friend google figured that one out...

- bought the following items: 2.5-ton capacity jack, 2 3-ton capacity jack stands, 4 tire chocks, good socket set (200+ pieces), breaker bar, torque wrench, impact driver (sure, always easier to simply drop the problem off at the shop, but I had a feeling that was going to be expensive, so I decided to spend my money wisely)
- placed tire chocks on each side of each front wheel to help keep the truck stationary
- used breaker bar and 21mm socket to loosen lug nuts on rear left (driver's side) wheel -- those suckers were on there tight! Way above the 80 ft-lbs specs. Sure, I respect mechanics.
- jacked the rear of the truck, with load applied at the differential case (grease geeks call it a half pumpkin. To me it looks like a big circular chunk of metal with a bunch of bolts around the perimeter, located between the rear wheels)
- placed jack stands at the rear jack points per user manual instructions (bottom sides of vehicle just in front of the rear wheels)
- slowly lowered truck onto the jack stands
- removed loosened lugs and removed wheel
- for added safety, placed wheel under truck half-way, just in front of jack stand

Ok, stage was set to take a look. Next challenge was removing the plastic shield covering the fuel filler neck. This is was I did (should have done):
- attemped to remove the two bolts holding the shield to the body of the truck, shearing both in 30 seconds flat (would have been better to first spray a good penetrating oil like PB Blaster). Shearing those bolts seems trivial to me now but at the time it really sucked. I thought about giving up. What am I doing anyway. I'm not a mechanic. A computer geek at best. Return the toys, pay The Guy whatever, sell, and lease. No! I needed to push on...
- then I yanked on the shield near the smaller circular clasp type things, all 3 of them (would have been better to use a small screw driver to apply pressure at the clasp). Nothing broke this time fortunately.
- then I looked at the big mess that just fell on the floor, a good half bucket of sand, salt, rocks, rust, and maybe a whiff of the kitchen sink
- beyond that, I see four screws holding the neck up and a couple of clamps, connecting the lower ends of the neck to rubber tubes

Verification complete. You've got two pipes running the length of the filler neck. The larger pipe takes the fuel, with the smaller pipe (breather pipe) allowing air to escape from the tank as it's displaced by fuel during your weekly gas station mugging. In my case, half the breather pipe didn't exist anymore, ashes to ashes. And the fuel pipe was rusted. Rusted real good.

I make a call to my trusted, well respected -- local -- Hyundai dealer, first to Parts. I know beforehand that I can get a new filler neck online for about $90 (but I live in Canada, so there's that exchange thing, taxes, shipping, more taxes, brokerage fees, and waiting of course). Parts guy quotes me $185 but he needs the VIN to be sure. Me and the VIN call back. In a moment of beautiful monetary magic, my quote turns into $218.48. Plus taxes.

Next up, Service. The Guy. He quotes me $400 (4 hours labour). What? We're talking about 4 screws, 2 bolts, and 2 clamps. After some thought provoking, let me look into it kind of thing, I get a final quote of $150 labour.

Why stop there. After all, there's sanity to be had in consistency. I like sane. Sane real good.

I call up another not-so-local dealer. Parts guy: $161.41. With the VIN: $161.41. Screw the magic. Service guy: $500. WTF? Yet more deep thought later, after a call to the general manager for motivational purposes: $150.

What now? Should I buy the part and do the work myself? I can jack the truck. I've got lots of shiny new tools. I even have some fancy work gloves so my keyboard friendly hands don't get dirty. If it wasn't for those darn sheared bolts! And maybe a little bit of I-don't-want-to-start-a-fire kind of fear. Fuel vapour is nasty, dangerous stuff.
But now there's principal to be had. Money vs. knowledge. Which pulls trump? I needed to prove a point.

How I replaced the filler neck:
- confirmed that my gas tank was only 1/4 full (who wants to clean up a fuel spill)
- purchased the neck for $161.41 (called in the morning, ready for pick up at noon). Also bought 4 new screws and the fuel pipe clamp. The other clamp (the smaller spring type clamp wasn't in stock).
- sprayed PB Blaster on the four screws near the gas cap, top and bottom, the night before. Also sprayed the clamps.
- next day, removed the two rubber hoses: getting the fuel pipe clamp off was a pain, but the vicegrip-screwdriver-patience trio came through. With clamps removed, lifted each hose up a bit with a small screwdriver and sprayed WD40 between hose and pipe and let it sit for a few minutes while I tackled the 4 top screws. It does take some effort/patience, but eventually the hoses twist off.
- stuffed the end of each disconnected hose with some paper towel -- I don't know if this step is necessary but it made me feel safer while I fought the other end of the pipe
- removed bottom two screws with ease
- top two screws would not budge. Even after hammering away with an impact driver, I still stripped the heads.
- decided to drill out the heads with a titanium coated drill bit, keeping the bit oiled to manage heat (I just used motor oil, but I guess WD40 would sort of work). The heads didn't come off at once, but a twist or two with some pliers popped them off, to the delightful sound of the filler pipe crashing to the floor
- attaching the new filler neck was, ironically, the easiest step in this journey. So easy in fact that I don't need to go into detail. I just reused the old smaller spring clamp, removing the paper towel of course and giving a quick wipe down of the rubber tubes inside and out. No need to worry about extra seal for the filler neck/gas cap, as the filler neck comes with a rubber grommet and the final seal is air tight.
- to reconnect the plastic cover, I had to drill and tap the sheared bolt studs. I want with 5mm bolts and washers.
- torqued the lug nuts to 80 ft-lbs

Clear the code and held by breath for the next few days when ever I cranked the ignition. No lights as of yet.

None of this would have been possible, for me, had I not googled "p0455 santa fe" and found this thread. So thanks again and I hope my experience helps at least one other person.