Check Engine Light is on; Also got "tighten fuel cap" message

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by wmkess, Jan 11, 2013.

  1. wmkess

    wmkess Rockstar 100 Posts

    The other day as I was driving to work I got the message "Tighten fuel cap" in the odometer display. The check engine light didn't come on. When I went to lunch I didn't get the message but the check engine light was on. When I turned the truck off I reinstalled my fuel cap. When I left, the light was still on. It has been on for about 70 miles now but haven't received the "tighten fuel cap" message again. I also have yet to get it scanned to see what the error code is.

    I have the repair manual and have read a few other posts on how to handle the issue if it is the solenoid that controls the tank pressure but I had a few questions out of curiosity since I have yet to check the repair manual. The primary one is if the check engine light comes on and the problem is fixed, will the light go off on its own or do I have to disconnect the battery or something to reset it? The other thing I was wondering is if these issues with gas tank pressure are relatively common and expected for a model as old as mine?

    BTW, I have a 2005 Silverado with the 5.3L with ~96k miles. TIA.
  2. j cat

    j cat Epic Member 5+ Years 1000 Posts

    these fuel cap codes are common if you fill the tank to the max...then the canister and vent valve get pluged with the black canister goo. charcoal..

    you can get this also if you have the engine running and refilling. the light should go out on restarting. every time you restart the PCM goes into a diagnostic mode checking all onboard systems.

    if it continues I would pull the code and post here for more info.
  3. wmkess

    wmkess Rockstar 100 Posts

    Thanks for the reply.

    I do fill my tank up every time I get gas, as I'm one of those people who check my mileage every fill-up for every vehicle I own. I also never pump gas as my vehicles are running, just smoke (just kidding!).

    I plan on swinging by one of my local auto parts stores tomorrow morning and getting the code read. I'll post it when I find out.
  4. Enkeiavalanche

    Enkeiavalanche Loving the Outdoors Staff Member 5+ Years ROTM Winner 5000 Posts

    If it's P0449 We know what it is.....:gasp: Keep us informed..
  5. j cat

    j cat Epic Member 5+ Years 1000 Posts

    so with the filling up with big swings in temp this then causes the canister to create the black goo that causes these issues. post the code.

    removal of the vent line and checking for this black material would indicate this is the problem. when it gets real bad you will have trouble refueling the fuel will spit back and you will have to fill very slowly.

    never fill it up then park in a heated garage that is the worst case. could even burn up the garage etc...
  6. gsvar200467

    gsvar200467 New Member

    Had the same thing happen to me the morning I was going in for new pistons and rings. Had to change evap vent valve. Coulda done it my self cheaper but just didnt have time.
  7. Enkeiavalanche

    Enkeiavalanche Loving the Outdoors Staff Member 5+ Years ROTM Winner 5000 Posts

  8. wmkess

    wmkess Rockstar 100 Posts

    Got it checked today...the code was P0445.
  9. Jamm3r

    Jamm3r Member 2 Years 100 Posts

    Check the fuel cap O-ring first as they do not last forever. If there are cracks replace the whole cap and that may very well clear things up.
  10. wmkess

    wmkess Rockstar 100 Posts

    Will do. Have yet to check that.

    Also, anyone have an input to that service code I posted? From my understanding its the evap canister/solenoid. I plan on checking the circuit to it, then checking the filter and then replacing the solenoid if needed.

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