1999 GMC Sierra diagnosing trouble codes

1999 GMC SIERRA
190,000 MILES • V8 • 4WD • AUTOMATIC
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BOSSBOGG1
  • MEMBER
  • 1 POST
My 00 gmc sierra 1500 has codes po171 and po174 where should i start to do repairs myself. the fuel filter has been changed after problem started.
Feb 7, 2010 at 4:35 PM
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BLUELIGHTNIN6
  • CAR REPAIR CONTRIBUTOR
  • 16,542 POSTS
check vacuum hoses for splits, kinks and proper routing. MAF sensor, air induction system, throttle body, intake manifold, PCV system and EGR valve all need checked for vacuum leaks as well. Check exhaust sytem for leaks / damage. Test oxygen sensors.
Feb 7, 2010 at 4:40 PM
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