got truck checked out,replaced pcv hose passenger side, 3 weeks later throws codes again,any suggestions?
p171,p174 codes on 2004 Ford F-150 Heritage
You have a vac leak. You have either missed other vac hose/connections or you have a intake manifold leak. If you would provide more info on your truck I believe there might be a TSB on that truck. Contact me at firstname.lastname@example.org.
Vacuum leak or a failed MAF sensor.
If it is a 4.2 liter engine you will have to replace the intake spacer.VERY COMMON problem.