P0455 Code, where to look?

Discussion in 'Engine & Drivetrain' started by strad, Oct 12, 2018.

  1. strad

    strad Full Access Member

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    2005 Suburban Z71 with a 5.3. The code is Evap large leak detected. Reasonably sure it is not the gas cap. I replaced it with a brand new AC Delco part, because the rubber was showing some signs of wear. The code is on its way back (has not set the check engine light, but has put a message in the information center to check gas cap). I've looked at all the rubber tubing I can see easily in the vicinity of the rear axle and filler neck from underneath. I do not see anything amiss. There are no other codes set or pending.
     
  2. Erickk120

    Erickk120 Member

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    Do you get pressure build up after parking from a trip and taking the gas cap off? Do you smell fuel gas in the air after driving it and coming out of it? I had the same exact symptoms as yours at the beginning with no check engine light, replaced the gas cap with a AC DELCO one, to no avail, I would get it triggered every time the weather was chilly, but eventually I got it every day and later I developed the other 2 symptoms I posted the start of this response and a check engine light, I noticed my charcoal canister was covered in transfer case oil, and I had replaced the vent and purge solenoid with aftermarket ones previously, that didn't help, I didn't take the time to diagnose the problem thoroughly but pulled the trigger and replaced the charcoal canister and both vent and purge solenoids with AC Delco ones, that fixed all the symptoms and got rid of the large leak code and check engine light. Most of the time if the lines are fine it just ends up being the purge valve.
     
    Last edited: Oct 12, 2018
  3. strad

    strad Full Access Member

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    Have not noticed any fuel smell, and not much if any pressure at cap. I knew where the purge valve was located but didn't know where the charcoal canister was located. But you said yours got covered in transfer case oil so it has to be nearby! I'll take a look in there. I guess the purge valve likes to stick open which vents it constantly.
     
  4. Erickk120

    Erickk120 Member

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    When it comes to EVAP problems they can be hard to diagnose, especially if you don't have things like a smoke machine or one of those expensive computers, so I've always replaced the inexpensive things first before getting into the more expensive ones, that or get it diagnosed for 100-150 at a shop, I replaced the canister and both vent and purge since it was about the same anyways, and I knew my lines were fine and weren't leaking or cracked. Some people don't mind having the annoying chime every time they get in their truck, or the check engine light, but I my self hate seeing anything in the dash light up. I hope it is just one of the solenoids and not the canister, or something like a line.
     
  5. Big Mama

    Big Mama Full Access Member

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    You might try just soap and water spray bottle like looking for a leaky tire. It won’t bubble as much but you’ll see a vacuum somewhere just use very little. Also check your intake.
     
  6. MCAT069

    MCAT069 Full Access Member

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    Check Amazon; I got a charcoal canister, purge and vent solenoids for 70 shipped for my 04 8.1 burb last week. Those three cleared my P0455 code.
     
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  7. Doubeleive

    Doubeleive Elite Member Supporting Member

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    easiest fix is to drop two bills and replace the hole shebang, (canister, 2 solenoids) or less depending on what manufacture you go with.
     

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