Computer codes

I have a 1999 Ford Explorer that has 125,000 miles on it. The check engine light came on about 2 weeks ago. I order the Innova 3110 scan tool. The two codes that are coming up with this device are PO171 and PO 174 - and that is all I have to work with. I need guidance as to where to start in the area

Here’s three things to try.

  1. Clean the MAF cleaner with MAF safe spray.
  2. Look for air/vacuum leaks at the intake.
  3. Check the fuel pressure.