Light went on a couple of days ago. Autozone gave me #0455 which is emissions leak (large). Could this just be the gas cap or are there other things I need to check for?
Thanks!

 

There are a lot of parts to the testing of the tank.
The 455 code says the inital test has failed and stops all the other testing that is done. Phase 0 test. There are 5 test phases.
Could be the cap but also a fault with the cansiter vent solenoid, the vapor manegement valve or hose connections in the system.
Sorry it's not very easy to discribe due to the length of all the testing that is done by the PCM just for phase 0.
You may be lucky to find something on a check out otherwise you would need to know how the system does the testing and what parts are involved.
Good luck.

 

In other words, if the cap doesnt fix it then Ill take it to a mechanic becuase I have no clue what all that other stuff is.
Thanks for the quick reply and the info!

 

[QUOTE=gata119]Light went on a couple of days ago. Autozone gave me #0455 which is emissions leak (large). Could this just be the gas cap or are there other things I need to check for?
Thanks![/QUOT

I currently have that code and it is because of the plastic insert in the gas filler neck. The plastic insert has a piece broken off that makes contact with the gas cap to seal the fuel system.

 

i have a 1997 f150 supercab. i have had a check engine light on for the past month. yesterday the gas tank started leaking gas from the top as i filled my truck up. i will fix it today but am sure this is the reason for the light.
for the last month i had a faint gas smell when i was outside of the truck on the drivers side.

 

I used a two part epoxy called cold weld, it works with gas. First stuff a rag in the filler neck so nothing falls in the tank. Mix enough to slightly overfill the hole. Let it firm up a bit before you use it. Apply to the hole, popsicle sticks or plastic knives work well. There is a trick to it if its wet it runs if its dry it dosen't stick. Use wax paper if its a big hole it will hold the epoxy in place until it firms up enough and it will come off easily. Before the epoxy dries all the way shape it with a utility knife blade, get it as close as you can without taking to much. Keep the top edge flat and consistent. Let dry then sand smooth taking care not to damage the plastic. Vacuum out the filler neck then remove the rag. This repair saved me from replacing the filler neck. The check engine light is off and it passed inspection.