1. Welcome to PlowSite. Notice a fresh look and new features? It’s now easier to share photos and videos, find popular topics fast, and enjoy expanded user profiles. If you have any questions, click HELP at the top or bottom of any page, or send an email to help@plowsite.com. We welcome your feedback.

    Dismiss Notice

b&b,need your expertise

Discussion in 'Chevy Trucks' started by wirenut, Dec 29, 2010.

  1. wirenut

    wirenut Senior Member
    from nh
    Messages: 507

    my 04 1500 z71 failed inspection on a p0442 code..small evap leak
    where di i start...?

  2. GSORK

    GSORK Senior Member
    Messages: 128

    A lot of time its a bad fuel cap or a loose cap. Google the p code .
  3. wirenut

    wirenut Senior Member
    from nh
    Messages: 507

    thanks will try
  4. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Many are fixed with a simple fresh gas cap to replace the old one that's no longer creating a tight seal. Also get a few here and there where a few pin holes develop in the steel section of the filler tube or the clamps rust off so look over the filler assembly as well. If you get that far and still have the same issue go after the vent valve solenoid which is very common too as they'll stick partially open. Search "EVAP" as there's several decent threads on the subject here.
  5. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    most are NOT gas caps any more these days. thats such a old mith.

    gm has problems with the location of the vent solinoid on them getting full of crap and leaking. there is even a recall on these. and the part is updated to move it to a better location.
  6. RacingZR

    RacingZR Senior Member
    from Maine
    Messages: 398

    Not a GM but had the exact same code and error on my 03 Dodge and it was the fuel cap.
  7. bill7101

    bill7101 Member
    Messages: 34

    At the shop i work at most of the ones i get with evap codes it is usually the vent valve that went to heck
  8. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    You'd be surprised by how many are fixed with a gas cap or filler neck. Not necessarily GM trucks, but lotsa other makes. It's hardly a myth.
  9. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    might be but are you doin a full drive cycle to verify its fixed ? or does the cust say ah screw it and leave it on for a year and not tell ya. ?
  10. 06Sierra

    06Sierra PlowSite.com Addict
    from Maine
    Messages: 1,328

    Sorry to hijack your thread wirenut. Would a bad vent valve cause a gas smell? No SES light or stored codes. First noticed it late last winter, it went away over the summer and is now back. There are no leaks and the smell is coming from the filler area.
  11. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Cube might but I don't because I don't let anything out the door unless I'm sure it's fixed. Change the cap, check the filler and pull 15 hg on the system for about an hour. If and only if it maintains then it goes out the door knowing it's fixed for sure. No need for a monitor drive cycle which is a potential waste of very valuable labor time anyway if you didn't get it the first time.

    The quarter turn "click" caps are some of the worse at failing to properly seal. There's four different styles that fit about 80% of the common applications on the roads today and I always stock at least a couple of each just due to their common failure.
  12. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412


    If you've got the equipment to find evap system leaks in the first place, then you'd be a fool to not test your repair, no matter what it was, before the vehicle leaves. Waiting for an evap monitor to run can waste a ton of time... especially in the winter months.
  13. stacks04

    stacks04 Senior Member
    from ct
    Messages: 119

    Yeah, most ARE gas caps with the lower percentage being small leaks elsewhere.
  14. wirenut

    wirenut Senior Member
    from nh
    Messages: 507

    thanks all.
    is the vent valve accessible on a 04 stepside or does the tank have to come out ?
    also i heard you can use a unit from a cavalier which is the same and doesnt cost 200 bucks the stealer wants
  15. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    No need to pull the tank. It will be located either on the side of the left front bed mount bracket or on the rear of the tank just ahead of the rear axle.

    Never tried a Cavalier valve but before they were available in the aftermarket for $40 thus had to be sourced from the dealer I used to use an '06 Suburban for an application for all the '04-newer trucks. Same valve as the actual application called for but cost $39 instead.
  16. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    Half the CELs we see at work are EVAP codes. 80% of the time they just bought fuel, the cap is loose.
  17. damian

    damian Senior Member
    Messages: 330

    i wish most of my small evap leaks were gas caps. better get out the smoke machine with flow meter,and the scan tool to make the purge and vent valves close.
  18. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    that was our shop i worked at my self . not many caps . was valves / screwed up lines / rotted out fuel filler necks.
  19. fordmstng66

    fordmstng66 Senior Member
    Messages: 527

    My buddy Is a mechanic, and he ran into te same problem with the vent solenoid. Like you said the gm sells an updated kit to fix the problem.
  20. wirenut

    wirenut Senior Member
    from nh
    Messages: 507

    thanks for all the help,
    i pulled the can from the side of the tank blew it out and put 12v to it and heard it working so i put it back will see what happens also flipped the rubber seal on cap over. now is that box i took the hose off the charcoal can ? would that be a possible prob ? also where is this other valve on the engine located and whats it look like? will that give the p0442 code ?... sorry for all the ?'s