anyone familer with evap codes? non camaro related?

Discussion in 'Engine Topic' started by Rich 81 z28, Dec 30, 2014.

  1. Rich 81 z28

    Rich 81 z28 Veteran Member

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    i was wondering any one could maybe steer me in the right direction. I have an 08 Yukon 5.3. the po 449 code started a month ago.. I did a little reading and replaced the purge solenoid with the new update one and wiring pigtail that goes in front of the gas tank. reset the code and it stayed off to for about a week.. ran the code again, po 449 again. so I replaced the solenoid on the engine. reset the code.. [and for good measure I added seafoam to the tank] light came right back on a couple of hours later, scanned the code. 449 again. I threw a gas cap at it for could good measure. reset the code.. came right back on.

    I have gone back and put the GM solenoid back on the engine and I am back to the light being off for a couple of days. I have rechecked all connects. they all seem fine. the truck has about 75k on it. it is bone stock with the exception of laser iridium plugs.

    the only thing I can thing to do from here is a smoke test which I will have to take to a shop to do.. anyone have any ideas before I go that road? thank you for the help.. Rich
     
  2. Damon

    Damon Veteran Member

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    Last time I ran across one of them it was the seal on the ring that holds the fuel pump/sender inside the tank.
     
  3. Rich 81 z28

    Rich 81 z28 Veteran Member

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    that could suck.. I never seem to get off easy.. its really strange the way its acting. almost seems fuel level driven.. guess I have to find a smoke machine or open the wallet.. lol
     
  4. Bobby Schulz

    Bobby Schulz Veteran Member

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    I have seen bad solenoids right out of the box. The front one most of the time. Seems the aftermarket has not quite gotten that one right.

    You can also unhook one of the solenoids and air test it for a leak on the lines/o-rings.
     
  5. ssenay72

    ssenay72 Veteran Member

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    this will sound stupid but check your gas cap. Ive seen evap codes for a loose/bad gas cap.
     
  6. Mike N

    Mike N Administrator Staff Member Lifetime Gold Member

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    P0449 is pretty specific to the vent solenoid circuit. A loose gas cap, inoperative purge solenoid etc will not trip a 449 code. You may have gotten a junk part right out of the box.

    Get your hands on a scanner with bi-directional test capabilities and cycle the vent solenoid to verify operation.
     
  7. Joekool

    Joekool Veteran Member

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    The EVAP monitor doesn't run completely unless there are specific conditions (cold soak time - usually 6-8 hours, fuel level in a certain range - usually between a 1/4 and 3/4 tank of gas and so on down the check list). That is why an EVAP fault can take an hour, a day, a week or a month to set depending on if the conditions are right.

    Your code is like Mike N said, it is a circuit code, 90% of the time it is a part fault but there is a chance you have a wiring problem or a failed PCM driver. A simple test using a scanner capable of commanding the valve can have you pin pointing the problem in 15 mins instead of shotgunning parts at the vehicle.
     
  8. Rich 81 z28

    Rich 81 z28 Veteran Member

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    Thanks for all the help. I thought threw the 2 purge valves at because I read it was common. They even have a tsb on it. My friend is a master and we talked before I did it since he is not local. That said it's going to dealer next week. It stop falls under the 8/80 emissions warranty for most parts. Either way they said they would fix for free if under the warranty or charge me 100 bucks to fully diagnose it. I thought that was win / win.
     
  9. Rich 81 z28

    Rich 81 z28 Veteran Member

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    Ps. I had checked and replaced cap too. Since it only has 75 k on it. I figured it was a simple part failure
     
  10. Mike N

    Mike N Administrator Staff Member Lifetime Gold Member

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    Evap isn't covered by the 8-80, only the catalytic converter and PCM are.

    Joekool is correct that certain conditions need to be met to run an evap monitor, however a circuit failure will illuminate the SES light whether those conditions are met or not. The evap monitor itself is non continuous, meaning the PCM isn't always looking at it. There is a components montor that is continuous, so if the PCM doesn't see a component (because it's dead, missing or an open/short in the harness) it will turn the light on and set a code.

    If all else fails, change the 02 sensor. :p
     
    Last edited: Jan 1, 2015

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