engines codes

2003 GMC SIERRA
72,000 MILES • V8 • 2WD • AUTOMATIC
Avatar
BILLB55
  • MEMBER
  • 1 POST
Codes PO171&PO174. Just replace MAS about a week ago with a reman. Check engine light is on again. Reading the codes above. What should I check next.Changed plugs and wires less than 20,000 miles ago.
Jan 13, 2011 at 10:27 PM
Advertisement
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.
Avatar
JACOBANDNICKOLAS
  • AUTOMOTIVE REPAIR CONTRIBUTOR
  • 110,190 POSTS
the codes indicate a lean mixture on both banks of the engine. Check for vacuum leaks first. Check fuel pump pressure. A restricted fuel filter can restrict the fuel supply. Go to our homepage under the DIY section for direction to check fuel pressure. My first guess, however, is a vacuum leak.
Jan 18, 2011 at 9:28 PM