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Edited to add: 2005 EX Less-Special-By-The-Day Edition. 5 speed.

I just put a new NTK 24242 O2 sensor on our car and figured I might as well see if I can make heads or tails of the P0497 and P1457 codes we intermittently have.

History of the relevant pieces of the car:

• My wife had the throttle body replaced to address some issue the car was having. This was shortly after we met (5 years ago) and I don't remember what the issue was, etc.
• I put a new OEM (from Majestic) CVS solenoid valve on last March.
• Some time in the fall, I re-zip-tied the CVS solenoid valve on following the suggestion here.
• The gas mileage has been kind of lousy since early December. It got really bad when the brake caliper was dragging, but it still isn't where it should be. I mention this because the mileage was pretty lousy before I replaced the CVS solenoid valve, like maybe we've got a vacuum leak somewhere.

It's been intermittent EVAP codes for a while now. It's starting to get old. I downloaded TFM (The Factory Manual, what were you thinking?) from a link on the forums. ezone says here that this manual doesn't cover North America, which might explain why the diagram on page 11-29 doesn't include a CVS solenoid valve or possibly a bypass valve (if this car has one?) :-/

So, at this point I'm feeling kind of stuck. I have a hand-held vacuum pump that has a gauge on it, a DMM, and a DC bench-top power supply. I can unhook vacuum lines from the things they're attached to, apply vacuum, see if I can pull vacuum, and see if it holds, but I don't know what's normally open/normally closed, or what valves I need to make be open or shut to put the system in the state it's in when it detects the code.

So, any suggestions on how to go about troubleshooting this one with the equipment at hand? Thanks as always.

Also, I know there used to be a post with a complete list of DTCs. I'll be damned if I can find it with search now. I'd love a link to that if somebody has it handy.

 
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I think the relevant pages on Majestic are these two:

https://www.hondaautomotiveparts.com...l--fuel-pipe-1
https://www.hondaautomotiveparts.com...-throttle-body

If they'd just make those damned drawings a little bigger, it'd be helpful...

 
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Here's what the new one looks like:



Identical except for being much lighter, which surprised me. All the charcoal in the one above was damp, but not wet. There was even some sort of mold buried in the middle of it. I'd say about the consistency of mouse poop, since I'm sure you handle that all the time! Really how would you know what the system is using to determine the position of the valves though? You just don't want to replace it because it's $100+ even shopping around on eBay. Do you? None of the ones I used are OEM, but the EVAP code is gone.

There's one 12mm bolt holding the canister on. I have no idea how you'd ever get to it without lifting the car up, but the hoses were easy enough except for the very top one, which was a quick-connect style. The filter is probably not worth replacing in a lot of cases; there's obviously a bypass installed even if the filter looks unused (which mine did). All the screws/bolts were completely rusted. A couple cents for a pack; you'll pay more for the shipping than the actual part.

 
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Not that you need to.

 
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Can you link to where you bought the screws/bolts?

 
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honda sells them, they'll be fairly cheap

 
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This is the website I ordered from. They have a phone and live chat, but no free shipping or anything: https://www.hondapartsnow.com/
You'll need to enter your car before it can pull up a diagram, but mine is showing the screws as: 93893-05010-08 Screw-Washer (5x10) and the bolt as: 93403-08020-08 Bolt-Washer (8X20)
The vent I ordered was aftermarket; I think I got it through Amazon. You might have to shop around a little. If you really want to go for broke, there's another purge control solenoid up front off the throttle body that uses the same screws. Congratulations! You've solved the mystery of the gas fumes coming off the tank of your 2001 Civic. De rein.

 
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Thanks so much for the information! I'm really happy I was able to fix the issue.....well not yet. I got my vent valve on Amazon too.

 
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Are these the screws you mentioned? Does it come with both? I tried salvaging the lower part but one of them I broke apart.

 
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Got everything back together a couple days ago and still no engine light! YES!

 
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from my 02 civic... P1457 code. I replaced the valve, not the whole box. The screws were really rusted out, and like you, the "nut" part of it came out of the cannister. I was able to reuse the
"nut" part, tapped them back into the cannister, and they held tight when I put new screws in. But, P1457 came back on after I reset the code, so I'm suspicious those "nuts" may be causing
the leak. I ordered some RTV and I'll reseat them and try again. If that doesn't work, I will replace the valve at the throttle body.

 
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I would be surprised. One canister shut valve I replaced I had to cut the head off both rusty screws. To hold the new valve in place I smothered the bolt/flange area in JB weld and ran a zip tie all the way around the canister. Hasn't leaked yet.

P1457 is a pain to troubleshoot mainly because there are no instructions in the service manual available on this site. I can try to provide some actual troubleshooting steps if you would like. You would need a vacuum pump/gauge and some basic electrical tools.

 
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Ericthecarguy just posted a 30 min video about dealing with p1457 on a 7th Gen civic on YouTube

 
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Thanks Colin, that was an education. Its funny, I recently watched ( ) , he also had a smoke machine. 45 minute smoke video and he gave up and used soap and water to find the leak, and it was the cannister vent solenoid valve.

Thanks Brotato, I don't have a vacuum pump/guage (yet?). I'll post if I have any breakthrough.

 
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With how rusty the CSV was I'm surprised that didn't take care of it.

 
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Very rusty, MA car with 203K. I had high hopes for the CSV too. When I get a chance I'm going to check all the connections
and rtv the cannister anchors.

 
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Look at some of the wiring back there too. I have seen a few with chewed up wires causing EVAP codes.