OBDII fault PO455 and PO401
 

Gents...

I have 2 faults reading...PO455 and PO401...

Can someone help direct me to what parts I need and
how can I fix it.

It's an older truck, 1999 F250 V10...I really cannot afford
to take it in for service.

Thank you in advance for your help.

455 is evap large leak. Coule be gas cap loose, bad seal on gas cap, evap line off or broken. Lots of things.

401 is an egr flow problem. Dont know much about the V10 so im not much help there.

The 401 sounds like the DPFE sensor is bad - or a hose is broken going to it - need to check into this more.

The 455 is like 06silvercrew said, something with the gas tank is leaking air into the system - as in, it's open to the atmosphere. Need to check all the hoses, make sure the gas cap is on tight, AND that the filler neck isn't rusted through.

If you want to work more on it, and can do the work yourself, we'll work with you on it ;)

P0401 = take a vacuum pump, put it on the top of the EGR start the vehicle, pump the gauge, if the idle changes or the truck dies, 99% of the time = DPFE Sensor. Check the two hoses going to the DPFE as they tend to be brittle and break also. Havn't ever seen a EGR issue with those yet.

P0455 can be tought as it could be a loose gas cap (make sure it clicks) maybe a bad cap, have seen the EVAP unit (cant think of the proper name right now) the big black plastic deal by the spare tire that is by the fuel tank (I have seen those broken before) Check the fuel filler hoses. Being it's a large leak you should be able to find something visually, unless you have an EVAP solenoid stuck open.