Jump to content

P0455 Evap Leak

Coop8202
 Share

Recommended Posts

Coop8202 Enthusiast

Coop8202

Posted
Posted

Hi, I have a 2008 GMC Sierra with the 5.3. I got a P0455 Evap code a while back. I can clear it but it comes back within a few days. When filling the truck up, when the pump shuts off gas spews from the canister area underneath the truck. I can usually always smell a raw fuel smell after driving from the bed area. Thanks! 

sefiroxx Enthusiast

sefiroxx

Posted
Posted

Check hoses and canister. The system should be sealed. A break will on the "seal" will set the code. In your case, hose from tank to canister is compromised.

tbarn Senior Enthusiast

tbarn

Posted
Posted

System is normally open. Pcm closes the vent valve to test.

sefiroxx Enthusiast

sefiroxx

Posted
Posted

Evap is closed when verticals is off. Vapors from fuel tank are passed to the canister.. If pressure builds, the system has an over pressure release valve at the canister.

When the vehicle is running, a valve opens at a certain rpm to allow the stored vapors to be introduced into the intake.

riverbanks Senior Enthusiast

riverbanks

Posted
Posted

Vent valve is open when vehicle is off,purge valve is closed when off,a guy did a test somewhere on here a ways back,purge valve opens on decel,he hooked up a test light to watch,now he didn't test light the vent valve,so during evap leak test,purge opens,vent closes for small leak test,then opens for large leak test?

Coop8202 Enthusiast

Coop8202

Posted
  • Author
Posted

What’s the easiest way to test all of this without pulling the bed?

sefiroxx Enthusiast

sefiroxx

Posted
Posted

Purge opens at certain rpm. Prior to rpm threshold, the system is sealed and there is some pressure which the computer checks with a pressure sensor. If no pressure, the code is set.

If leaking on fill, then there is a hole somewhere (100million + cars don't leak on fill)

sefiroxx Enthusiast

sefiroxx

Posted
Posted

Lots of write ups out there. In general, on earlier cars (20 years +) the valve was opened or closed when engine was warm and in gear and moving.

Later engines, once the engine warms up, the cake is pulse width opened. Small amounts in idle, larger amounts as rpm increases.

The 440 test occurs at one of two points. On some earlier cars, with a pressure sensor and the system purge valve known to be off. In a pulse width system, the system will measure vacuum pressure, shut the valve off and measure pressure again. If the vavuum pressure doesn't change enough, it will set a code.

Coop8202 Enthusiast

Coop8202

Posted
  • Author
Posted

I always shut the truck off when filling it up, but before shutting it off, it’s at idle of course, so around 800-1100 rpm

  • 5 years later...
Coop8202 Enthusiast

Coop8202

Posted
  • Author
Posted

Update: Top of fuel pump rotted out due to design of tank/pump and debris sit down in there. 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Latest Articles

  • Posts

    • Atlas
      Gas Prices

      By Atlas · Posted

      Welcome back! No, it definitely doesn't pass the sniff test. Even "ceasefire" needs an alternative definition these days.    $5.29 at Kroger today
    • bluev8
      Intermittent no-code issues on 2022.5+ V8 trucks — what did the shop fail to capture?

      By bluev8 · Posted

      That makes sense, and I think you are describing the real product problem. Capturing data is the easy part. If the owner or technician has to manually dig through five minutes of millisecond-level logs, the product has already failed. The device would be at the ECM harness, not at the OBD port, so I agree that data retrieval and event marking need to be thought through carefully. The way I am thinking about the architecture is: The recorder itself should not depend on a phone, app, Bluetooth, Wi-Fi, or cloud connection to capture the event. It should always keep a local rolling buffer and lock the event locally. A button, phone app, or small cabin device would only act as an event marker. If the driver feels a stumble and presses the button 10–30 seconds later, the pre-buffer has to already contain the useful data. For data retrieval, the practical options would be a sealed service USB lead, Wi-Fi download, or a phone/cabin companion device. I would not expect the owner to remove the ECM-side module or work with raw files directly. The cloud or AI side would be for interpretation, not for capturing the event. The truck may have no connection when the issue happens, so the evidence has to be saved locally first. After that, cloud processing could help decode the data, compare it against baselines, and generate a readable report. For the first version, I would keep the automatic triggers conservative and objective: driver event marker bus-off error passive voltage drop / brownout device reset FIFO or queue overflow a normally periodic message disappearing side-to-side communication mismatch, if the topology supports that For “learning normal,” I agree with your point, but I would not want to overclaim it as automatic root-cause diagnosis at first. A realistic first step would be learned baseline comparison for that specific vehicle and operating condition. For example, a value would only be compared against similar conditions: RPM range load / MAP throttle position gear / vehicle speed coolant and oil temperature battery voltage AFM/DFM state, if decoded and validated Then the report could flag things like: this periodic message disappeared compared with its normal timing this value deviated from this vehicle’s normal range under similar conditions the same abnormal pattern repeated after the same type of event the anomaly occurred together with voltage, oil-pressure, misfire, or communication changes But I would still call that “abnormal pattern detected,” not “replace this part,” unless there is enough validated repair data behind it. So the intended product would not be “here is a huge log.” It would need to be an event package: what triggered the capture how much pre/post data was preserved what changed before and after the event whether the device itself reset, overflowed, or saw a bus error selected graphs around the event raw data only as supporting evidence From your perspective, what would make this kind of report useful instead of just another datalog? For example: What are the top 5 parameters or events you would want highlighted first? Would you trust a learned baseline for that specific vehicle, or would you prefer fixed thresholds? How much false-positive flagging would be acceptable before you stopped looking at the reports? What would a one-page report need to show for an independent shop to take it seriously? For misfire, AFM/DFM, oil pressure, or U-code complaints, what would you want the tool to flag automatically?
    • scotthvac.net
      2022-24 halogen - led grille swap

      By scotthvac.net · Posted

      2024 Silverado 2500 HD LTZ grille no camera Parts list   84603331 84913656 84913657 84913654 84913655 84911567 84911568 85646092 85646093 85797921 85797922   11570637  x10-15   grille/bumper bolts 11546500  x10      grille clips 11571006  x10      push/retainer clips 11546454  x6       nut retainers 11611609  x6       M5 bolts 11610700  x6       molding/trim retainers
    • davester
      Replacement Radiator

      By davester · Posted

      And use RA's 5% discount code if you buy from them.  google for the code, one is always available.
    • davester
      Turning radius

      By davester · Posted

      Just don't turn the steering wheel as much?

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...