The codes are for an evap air valve failure. You'll need to buy a new Evap Canister Purge Valve from Nissan to fix the problem.

Here's what you have to do:
1) Get under the car behind the driver's side rear wheel and you'll see a black, plastic square box with the purge valve (it has a plug and a hose connected) and two hoses connected to it. There's three bolts holding the box in place. 2) Disconnect the three hoses and the plug and unscrew the three bolts. To drop the box, pull the rear of it towards the driver's side outside of the car and pull it back towards the rear (there's two pins holding it in place).
3) Once it's out, you'll see two bolts holding the purge valve in place. You definitly want to spray them with WD-40 and let them soak for 15 minutes (trust me! I didn't and snapped both bolts. Used JB weld and tie-straps to put the damn valve back in place). Be careful unscrewing the bolts.
4) Once the bolts are unscrewed, you can pull out the valve. I had to pry it out, so expect it to fight you. After that, just put the new valve in and put it all back together.

I noticed that I regained my power, my engine was smooth again, and the annoying hissing noise went away. The part costs around 85 bucks and you can only get it through Nissan.


(mods: put this in the How-To section please)

 

I am glad you got yours fixed, but I replaced mine about three weeks ago and the light is still on... after clearing the code, etc! and still engine isn't as strong as it was, and I am only gettin 21mpg... Used to get 24mpg, also replace the gas cap. Still don't know what the problem could be!

 

hey
i just wanted to post in george's first ever post in the 5th gen forum..and WOW, its a useful thread

 

...I've had others. I try to keep my whoring to the DC forum.

 

You probably have another leak. I know that I need to replace my right O2 sensor so the light's still on.

 

could it be the vaccum hose? or w/e they are called? i really want to get it fixed, but nobody seems to know where it's coming from etc..

 

Don't forget the charcoal canister, if you are getting EVAP Very Small Leak codes, more than likely your charcoal canister is cracked.

P0455 is EVAP Gross Leak, prolly your vent valve was stuck open.

 

That's exactly right. The code read "Major Evap Air Leak" according to Autozone. I got a better scanner from a friend of mine and was able to narrow it down to the purge valve from there.

 

Ok, it isn't a small leak code, it is a large leak! And how do you know if the vent valve is "Stuck open"? Since I swapped out the old canister with the new one, I haven't seen a performance improvement, and also haven't seen the code go away!

P0455 - EVAP Control System Gross Leak

 

It could easily be a loose hose or a hole in something. Really, a major evap air leak can come from anywhere in the evap air system, but to qualify as "major", it has to be something big. That's why I started with the valve as I couldn't find anything loose or any hoses disconnected.

 

my SES went off again, it does that a lot, but I am almost positive it will be back on this week.. and that's why I replaced the valve first, it was the cheaper of my options. and yet me, nor a mechanic can find a hole in the system or anything loose. dunno what else there is to check!

 

My SES light is glowing. I got it checked at Auto ZOne and got the code. Code is P1456. I checked the list and it means EVAP control system small leak (positive Pressure) No idea what this means. Can anybody help...

 

There's a laundry list of possible causes for that code. The Nissan FSM gives you a lot of information on how to diagnose it.

 

Howmuch Time it will take to DIY install new Evap Canister Purge Valve and EVAP cannister ? Can I do the de-install and re-install without putting car up on ramps or jacks? I have a quote of $565.00 to install EVAP cannister and cannister reg valve? Is this a PIA process to DIY? TIA mcmax02