I have a 2004 f150 fx4 non-heritage crew cab 5.4L. It has been giving me fits with the check engine light. It says check gas cap which I initially replaced with an autozone cap and it kept saying the same thing so then I bought a ford OEM cap. It now says the same thing with the new oem cap. I also was getting a code saying large leak in the canister system. I did a smoke test in the system and can't detect any leaks. I had an old wrecked 2007 F150 and exchanged the whole canister housing above the spare tire. I also bought a purge valve solenoid OEM part # 9u5z-9f945-c. I have searched all over the truck and just can't seem to locate where this solenoid goes. Can anyone point me to it's location. Much appreciated.

 

Please post the exact numeric codes if you want help. Thank you.

 

Sorry P0455 and P0457. Thank you!

 

PO455
Possible causes
- Missing or loose fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- EVAP canister or fuel tank leaks
- EVAP system hose leaking
- Fuel tank leaking
Do to bottom of pages to view vac lines!
http://engine-codes.com/p0455_ford.html
http://engine-codes.com/p0457_ford.html