P0442 code on my silverado

Discussion in 'The BS Topic' started by 80sz, Dec 2, 2017.

  1. 80sz

    80sz Veteran Member

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    Buffalo,n.y.
    Few days after getting truck back on road engine light came on. Had a random misfire ,o2 sensor locked and the small emission leak p0442. Fixed the intermittent misfire with new plugs and o2 sensor code went away. I can't find the leak in emissions . Truck keeps saying tighten gas cap. I bought a new one and it didn't help. Is there a way to find the leak without a smoke machine? I'd like to stay away from the dealer. Any area I can look at before have to bring it in?
     
  2. Mike N

    Mike N Administrator Staff Member Lifetime Gold Member

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    Spencerport, NY.
    Look at where the gas cap screws on the filler neck, the necks rust there and that will create an evap leak. Also look at the gas cap itself for a dried out or cracked o-ring.
     
  3. SRGN

    SRGN Veteran Member

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    Central NJ
    Vent solenoid could be starting to fail as well. Getting it tested with a smoke machine will save you money over parts changing.
     
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  4. 80sz

    80sz Veteran Member

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    That was my thought. I went to dealer and got a new gas cap. Didn't clear. The filler neck looks okay. I'll look it over again tomorrow.
     
  5. 80sz

    80sz Veteran Member

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    Should the solenoid give a different code? All I get is the p0442 .
     
  6. Mike N

    Mike N Administrator Staff Member Lifetime Gold Member

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    Spencerport, NY.
    The solenoid can still click open and closed and leak if there's crap caught in it, but not throw a solenoid specific code. When they do die, they will throw a P0449 code.

    Are you trying to keep the light off for inspection?
     
  7. 80sz

    80sz Veteran Member

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    It was off for inspection and passed. Came on few days after. It will clear for about 5-6 key cycles and come back on.
     
  8. SRGN

    SRGN Veteran Member

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    Central NJ
    5 to 6 cycles is probably how long it takes for you to complete a evap system drive cycle. Fuel level must be between 15 and 85 percent for it to run the evap tests. I just had to do this on a customers 2014 chevy 3500 this morning after replacing a purge solenoid. Only 72k miles on it.
     
  9. junkyardZ28find

    junkyardZ28find Veteran Member

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    Mar 4, 2012
    des moines, iowa
    hah-I have the exact same issue/code on my DD '04 Tahoe! I looked up the code and it read "typical fixes for this code are new intake gaskets" yeah whatever lol! I'm betting its something else but I'm more intrigued than anything else by it. Runs fine...may have to investigate this solenoid suggestion....
     
  10. Knuckle Dragger

    Knuckle Dragger Administrator Staff Member Lifetime Gold Member

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    Waddell AZ
    The purge valve is easy to check. Disconnect the electrical and the line going to the canister at the back or top of the valve depending on year. Start the truck and check for vacuum at the valve where you disconnected the line. If you have vacuum the valve is bad. I've seen a bunch leak enough for the leak code but not enough for purge flow code.
     
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