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p0171 p0174 '99 silverado

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by FergusonT, Jan 4, 2013.

  1. FergusonT

    FergusonT Rockstar 4 Years 100 Posts

    SES light comes on, throws the 2 codes. A lot of search results come up with, the trucks run poorly. In my case the truck runs fine. I just installed a fuel pump/filter. My dad actually just commented on how well it runs and sounds. I plan to clean the MAF tomorrow.

    It does have an exhaust leak starting, so thinking that o2 sensor might be something.
  2. shibby2oo8

    shibby2oo8 Member 2 Years 100 Posts

    Airtex pump from az? Codes happen after change?
  3. j cat

    j cat Rockstar 4 Years 1000 Posts

    with these codes when thrown at the same time is a vacuum leak. replace the PCV and make sure the hoses have no leaks cracks.

    could also be air intake hose leaking after the MAF. intake manifold gaskets typical vacuum areas of a leak issue.
  4. FergusonT

    FergusonT Rockstar 4 Years 100 Posts

    Also today it was warmer than yesterday, and on my way to work the check engine light went off. Not sure if thats worth mentioning. I'm going to replace the PCV and clean the MAF today.

    Is there any certain PCV that is recommended?
  5. j cat

    j cat Rockstar 4 Years 1000 Posts

    most stores have ac delco.

    make sure the pcv valve cover rubber fixture holds the valve securely.. check hoses before going to store including the other hose that the crankcase vents to the throttlebody area.

    check that the dip stick is securely seated.
  6. FergusonT

    FergusonT Rockstar 4 Years 100 Posts


    This thing is loose.....

    - - - Updated - - -

    My local advance has a Wells, Purolator, and Fram in stock. Worth it to wait for an ac delco?
  7. Conlan Rose

    Conlan Rose Active Member 2 Years 1000 Posts

    Always worth the wait. AC Delco makes your oem parts that are built to last. Buy it on amazon if you can it will save some money.
  8. j cat

    j cat Rockstar 4 Years 1000 Posts

    I believe that is the vac solenoid valve for the fuel evap system. that hose should go to the fuel canister .

    should be an O ring seal. may appear loose but as long as it has a seal it should be not leaking.
  9. FergusonT

    FergusonT Rockstar 4 Years 100 Posts

    I pulled it in the warehouse where I work and let it warm up, no fuel line chattering.

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