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Code P0455

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Old Jun 4, 2022 | 06:36 AM
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Code P0455

Engine light on with code P0455, Evap Emission System leak. Any common things that would cause this code? Where is a good place to start finding the cause of this code?
 
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Old Jun 4, 2022 | 07:08 AM
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Start with the gas cap. Make sure its seal and the sealing surface isn't damaged and that it is properly closed after fueling. If replacing, use only a Motorcraft replacement.

After that, it gets harder.

 
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Old Jun 8, 2022 | 10:19 AM
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Originally Posted by projectSHO89
Start with the gas cap. Make sure its seal and the sealing surface isn't damaged and that it is properly closed after fueling. If replacing, use only a Motorcraft replacement.

After that, it gets harder.
Found that the EVAP purge valve will not hold a vacuum. Ordered that and a new Motorcraft gas cap.
 
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Old Jun 8, 2022 | 10:36 AM
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It's probably not the purge valve... They always seem to bleed a little bit of vacuum.


 
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Old Jun 8, 2022 | 11:01 AM
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This one dropped 10"H2O in less than a minute. May have spent $$ un-necessarily?
 
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Old Jun 8, 2022 | 12:51 PM
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Start with the fuel cap.

 
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Old Jun 8, 2022 | 02:19 PM
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Yes, have one ordered.
 
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Old Jun 9, 2022 | 06:22 PM
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Question: If I pinch off the line going to the intake manifold from the EVAP purge valve will that take out all the things downstream of the purge valve? Thought I may try that and then look at my readings and see if anything changed. Currently the long term fuel trims are above +10%
 
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Old Jun 10, 2022 | 06:34 AM
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All that would do is give you a different fault code when the system discovers that it can't bleed up tank vacuum.

Don't wander off into the weeds down a rabbit trail.... Stay on the path that you've been given.



 
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Old Jun 10, 2022 | 08:21 AM
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Maybe at this point I need to make a smoke machine. Or recheck the hoses back at the charcoal canister? I know codes can sometimes take you in the wrong direction.
 
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Old Jun 10, 2022 | 10:35 AM
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Maybe, maybe not. Premature.

You need to do what was already recommended, reset the PCM's memory, then wait for the PCM to (eventually) run the EVAP monitor and THEN see if it passed or failed. I see no indication that you've done any of that.

If the monitor fails again with the same P0455, code, then smoking the system makes sense. Make sure you follow the explicit instructions for doing that.



 
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Old Jun 10, 2022 | 11:40 AM
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Originally Posted by projectSHO89
Maybe, maybe not. Premature.

You need to do what was already recommended, reset the PCM's memory, then wait for the PCM to (eventually) run the EVAP monitor and THEN see if it passed or failed. I see no indication that you've done any of that.

If the monitor fails again with the same P0455, code, then smoking the system makes sense. Make sure you follow the explicit instructions for doing that.
OK. I will reset the PCM. I have replaced the gas cap. Thanks.
 
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Old Jun 10, 2022 | 06:46 PM
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Took the truck out for a short trip. Looks like the EVAP system passed. I have one fail, $32 - EGR Monitor Bank 2, but no codes so far. Should I be concerned with that?
 
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Old Jun 10, 2022 | 09:07 PM
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I have one fail, $32 - EGR Monitor Bank 2, but no codes so far. Should I be concerned with that?
No. Do not poke around in that which you don't understand. Again, do not wander off into the weeds. Sounds like you're digging around into the Torque Pro data.

Just drive it and see if it posts any actual faults accompanied by a P-code.





 
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Old Jun 11, 2022 | 06:28 AM
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Only asking. Don't plan on doing anymore work as long as the code does not come back. No Torque Pro. OBDLink SX and looking at the diagnostic report, Mode $06 - On-Board Monitoring. Plan on taking it out today and see if the code comes back. Thanks for you help.
 
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