Hello I kept getting the codes p0171 and p0174. I read what they mean.I had my brother take the truck to the mechanic and he said it was an air vac seal that is leaking. I would just like to know what seal this is or where its located? My brother cant remember where it is. It's a 99 f150 4wd 4.6.
Thanks

 

A search here of codes P0171 and P0174 would be very helpful based on all the info that exists. As far as what the mechanic told you, I think some of the info got lost in translation Maybe he was talking about a intake manifold leak?