mnwolftrack

Hello, I've got a 2000 Civic CX hb that triggers a P1457 routinely. This is for an EVAP leak. I've already searched far and wide on the internet in general and found a wealth of info to at least get me started, but most of what I've found (beyond what I've done already) either requires a factory diagnostic scanner or a helm's (which I don't have).

Here's what I've checked:

1. I checked the canister shut valve by removing it off the charcoal canister, and first blowing through the valve to confirm it was open when NOT powered (it was open, which is correct). I then hooked it to 12V and the valve clicked properly and closed. I tried blowing through it again and it held solid. Note that My charcoal canister and shut valve are NOT under the car (every google search for this code said it was under the car!). Mine is under the hood, and while not new, it was not terribly rusty looking. I reinstalled the valve.

2. I've already checked the gas cap and filler neck and it looks good. The cap cap has always done the normal "swoosh" of air when I remove the cap to fill with fuel. Note that a loose or faulty gas cap should be causing P1456 though, and that's not my code.

3. I tested another solenoid (not sure of the name) but it is downstream from the canister and is found basically on top the intake manifold, visible when standing from the passenger side. This solenoid has a rubber line feeding into it from the canister, and has an exit line running directly into the intake manifold. Anyway, I tested this valve as well. When NOT powered, the valve is closed. When powered, the valve clicks, and opens (confirmed by blowing through it).

4. I've since cleared the code and am at half a tank of gas, so I don't think "overfilling" would be an issue at this point but the code will still come back on.

5. I've checked the rubber hoses in the engine compartment (where most of my EVAP stuff is located) and all looks good. Maybe the HB's are different and there isn't enough room by the gas tank to put the canister?

6. What other sensors might I be missing? I've run out of ideas of things to check. It doesn't look like the shut valve has ever been replaced, and I wouldn't think the ECM would have just decided to go faulty? (a TSB describes the possibility of a failed solenoid causing the computer to also fail). Fuel pressure sensor? How do I test it? It looks like there's a sensor above the gas tank (driver's side rear corner) that possibly has some tiny rubber lines near it, but I can't quite see what connects to it. I can only barely see a part # on it, but it does say Denso. It says something close to MX192000-5030 but the label was pretty dirty and I might not have all the #'s right. Not sure what this is?

mjme001

I also have this same problem, on my '99 Civic EX. Although I know far less about cars than you do. I took it to the dealer (big mistake, as always) I could have bought an OBD reader for the money I paid them to tell me that it's p1457 and to clear the code, which I could have done myself. But now the CEL has come back on. I'm wondering what to do next besides give them 500 bucks to change the EVAP purge solenoid controller. I'm gonna go back and check all the line under the hood as stated above.