P0455 Code on 21 Expy

3,518 Views | 48 Replies | Last: 7 mo ago by BlueHeeler
Sea Speed
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In reply to sts7049 • 9:51a, 5/19/25
AG
That's the one on the engine correct? I planned to pop it off and blow through it as I saw that the way to test it without being able to actuate it as It's normally closed, so being able to blow through it indicates failure. The vent valve off the canister is normally open.

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Sea Speed
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In reply to sts7049 • 7:20p, 5/19/25
AG
So somehow through all my looking things up about this issue (and being mentioned here, thank you) I never saw the incredibly simple purge valve test to see if it has failed.

Let the car cool off for about 4 hours after driving and started it up and felt the inlet for suction and sure enough it is pulling a vacuum immediately after starting so I am betting that is the culprit. I'll pick a new one up from the dealer tomorrow and hope that sorta the problem out. I'll check the codes after and just hope that cat code was erroneous. Then I am selling this thing.
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sts7049
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12:01p, 5/20/25
AG
nice, report back to see if i win internet points
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BlueHeeler
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12:19p, 5/20/25
AG
I don't think you can properly test the purge valve operation without fully knowing when it is supposed to be open and when it is supposed to be closed. Do you have a 12V battery charger? If so, remove it and blow through it with your mouth and see if applying voltage to it opens/closes it.

Keep in mind that you also have a fuel tank pressure sensor that may be going bad.
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Sea Speed
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In reply to BlueHeeler • 12:55p, 5/20/25
AG
Everything I read online stated that it is normally closed and if it fails open it will draw a vacuum initially when you start your car, which is what mine is doing. I was planning on doing the blow through test as well before I install new one as well.
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BlueHeeler
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In reply to Sea Speed • 4:03p, 5/20/25
AG
OK, yeah, that would make sense. I think the only time the purge valve is supposed to be open is when it is trying to pull a vacuum on the system in the test mode. Sounds like you may have found the issue.
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Sea Speed
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7:00p, 5/20/25
AG
Well I took the valve off and I can't blow through it so probably not this. Very frustrating. I'm going to have to take it somewhere now I reckon. Ugh.
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BlueHeeler
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In reply to Sea Speed • 9:20p, 5/20/25
AG
Keep in mind that it can hang and then close due to the messing with it. I would bench test/cycle it with a 12VDC power supply if you have one. That "large leak" error means it has to be this or the vent valve, I would think. I don't think it is typical for other stuff like the tubing to start leaking.
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BlueHeeler
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9:28p, 5/20/25
AG
I am going to also guess that the code you saw regarding catalyst efficiency could be caused by gas vapors going in to the intake at the wrong time and causing the O2 sensors to read too rich. If it were me, I would risk throwing away money on a new purge valve at this point. I think it's a 75% chance it's the problem from all the information you posted.
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Sea Speed
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In reply to BlueHeeler • 9:47p, 5/20/25
AG
I mean I have it on hand so may as well.
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BlueHeeler
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In reply to Sea Speed • 2:27p, 5/21/25
AG
I think the smoke test passing also basically showed it had to be either it or the vent valve. I hate evap systems. Let us know what happens!
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Sea Speed
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8:13p, 5/21/25
AG
Swapped it out and checked the codes. Cat code was gone. Cleared the two vapor codes and I am hoping they stay gone.
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Sea Speed
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8:47p, 5/25/25
AG
Several days without the light coming on so it seems this is fixed. Thanks to all for the insight and telling me to just put the part on and see what happens.

I think the solenoid was bad and as mentioned was operating intermittently which also as mentioned caused the cat code and previously caused an electrical code.

Very happy to have that behind me and not have to shell out to a shop and got a new tool out of it as well.
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BlueHeeler
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9:18a, 5/26/25
AG
Good deal. Glad you got it fixed!
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