2003 f-150 getting codes p1131, p0171, p0174, 0405
I have already replaced the MAFS. engine light continues to come back on & truck wont pass emissions. I saw 1 post saying maybe EGR sensor & 1 saying O2 sensor. the MAFS was over $100. dont want to fix whats not broke again. any suggestions??

 

I also checked hoses & see no cracks or leaks. wondering if its worth the time & $60 to replace ERG valve??

 

Pour some denatured alcohol in your tank to help pass emissions. Only a quick temporary fix but it'll work. Here's a link.
http://en.wikipedia.org/wiki/Denatured_alcohol
As for the error codes, good luck! Do some more research.

 

where can I find denatured alcohol? auto zone? & should I [pour it in a full tank?

 

Denatured alc. wont help if the mil light is on they wont even test it so your going to have to get those codes out befor you take it in to be tested.

 

i just changed the EGR Valve & reset the light. it's still idling a little rough, but not bad. I guess ill see if the light comes back on after driving it...

 

& the light is BACK ON!!!! replaced MAFS & EGR valve....??

 

When was the last time you checked out your spark plugs and wires?

 

Be sure to clean the wire connectors also, that may be why you're still getting mafs code

 

Replace the front o2 sensors and clear the codes.