2003 Chevy Tahoe Keep getting codes P0171 and p0174

2003 CHEVROLET TAHOE
65,000 MILES • V8 • FWD • AUTOMATIC
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SAPO24
  • MEMBER
  • 1 POST
I recently got my check engine light and changed my mass air flow sensor but the light keeps coming back on intermediately. Some days its not there. What else could be causing it to keep giving me a lean system failure.
Apr 9, 2008 at 3:44 PM
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MERLIN2021
  • ✓ASE Certified Mechanic
  • 17,250 POSTS
  • ASE Certified Mechanic
You may have a vacuum leak, get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs!
On yours with the plastic manifold, spray around the seams and the valves on the side, may need a new manifold or gasket..
Apr 9, 2008 at 3:48 PM
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