Nissan finally released a TSB for their EVAP Vent Control Valve issue. Goto www.nissanhelp.com. Many of us already know that Nissan made a mistake when they choose to vent the EVAP canister where they did. And because of it we have DTCs many times (P0455). And have even been the the dealership, but only to hear some crap about the gas cap being on incorrectly. I know this has been an ongoing issue with X's out there; I still have this issue and have even posted here about it. I'll be bringing in my X next week for the 30000 mile maintenance, and will sure as hell have them do this TSB finally.

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i had that issue around 60k and dealer wanted 580.00 for part and canister replacement. purchased the L shaped switch and replaced it myself. removed rear corner from bumper, inside wheel well cover, and loosened canister and dropped down enough to turn L shape switch and install new part. when i looked inside the old swith, there was a lot of dirt and the spring was bent inside.

SR - was the part you replaced the EVAP Vent Control Valve? (part# 14935-AM60A? Costs about $75?)

I'm having the same problem - haven't been to the dealership but I was thinking about just getting the part and doing it myself. You refer to it as a switch - I think there's a switch and a valve, sounds like it was actually the control valve that you replaced? Just wanna confirm that it's still fixed for you and I'm looking at the right part.
Haven't taken the panels off yet, just looking at pretty pictures in the service manual and TSB.

Maybe I'll try to clean out the valve first before springing for a new one.

Another thing I've been wondering about: Does having this problem cause any decrease in gas mileage or performance? As far as I can tell, it's just to contain vapors from polluting the atmosphere. But then again, I know just enough to be dangerous!

Thanks!

you are right, it is a valve and not a swith... L shaped. i dont think you are able to clean it. mine was broken in the inside.. it has a pring inside and looked liked it was crushed...and pressed..

it does take some time to take the rear plastic bumper off, the inner wheel plastic also.. remember those round fitting looking things in the wheel well.. you dont force them out... simply take a super tiny flat head to gently pull out around 1/4 inch and that will reduce the preassure and you will simply pop them out..

on the L shape valve.... you must turn it counter clock wise for it to release it self.. then use some type of lubricant to lubricate the o ring and press and turn clock wise............ it did not turn much into place... i would say using a clock... from 12 to 3 and it was replace.. good luck....

Could one of you educate me on this issue in simple terms? I'm not quite sure I fully understand this problem. Thanks in advance

I'm not a mechanic, but I THINK I can accurately describe it. Please correct if necessary:

There is a charcoal canister designed to collect gas vapors from the gas tank/filler hose that would otherwise get released into the atmosphere (environmentally bad). When the car is running, there is a vent valve that is suppose to open and release said vapors from the canister though a hose to the engine, thus burning the vapors instead of releasing them to the atmosphere.

The problem is that that valve can get dirt in it, and seize open. When that happens, a sensor detects a pressure drop in the line and sends code P0455. The fix in this case is to replace the valve and install a filter to keep the crap out so the new valve doesn't get hosed.
Installing the filter might be considered optional if the valve will last 50000 miles anyway and you don't mind replacing it on that kind of interval.

Also, water can get into the canister - if that happens, you need a new canister (expensive).
This can be determined by removing and weighing the canister. If it's over a certain weight (4.4lbs??), the excess weight is water.

All this to keep a little gas vapor from escaping top the atmosphere. For now, I'm just resetting the code.

If you do get this code frequently though, it could just be a loose or defective gas cap, as that will also cause a drop in pressure in the system that that sensor is monitoring. Same symptom, different problem. In my case, I was able to rule out the gas cap as I switched caps with my 07 Fronty and still have the problem on the X.

The official TSB calls for replacing the valve and installing the filter, but not replacing the canister unless if fails the weight test.

SR - the day before you posted that second message, I attempted to get at the valve. What a pain! Spent all afternoon, removed the panels, dropped the tire, removed that bolt that holds the canister in. Basically fighting my way in.
I could reach the valve and turn it, but could not get it to pull up and out. By this time, I didn't have much daylight left so had to put everything back together.

Now that I now how to get those panels out, I might give it another shot, as my brain was spent by the time I got to that point.

Did the valve pop out easily for you? even with dropping the canister I still found it very hard to work on (reaching in from behind). Maybe I was being to gentle on the canister and should have pushed it down/tried to drop if further to get a little better access. As I'm looking at this thing I'm thinking "you gotta be kidding me!" The service manual and TSB make it sound so easy. Maybe I should stick to computers (my normal profession) and just take the truck to the dealer.

All of a sudden dropping a few hundred doesn't sound so bad. Do you have any idea how much of that 580 was labor? I'm thinking about just getting a price to the dealer replace the valve only. Not sure if this is one of those deals where as long as it's apart, they just like to change both since it's more labor than parts intensive??

05_X Thankyou for your explanation; now I better understand this issue and will remember this as a possible cause if and when I get this trouble code. I really appreciate it.

funny you guys bring this up the day i bought X no sooner did i pull out of the dealership light came on ...u-turn.....the tech looked at it and said it was the gas cap so i never thought anythin of it .i have not had this problem and i now have 64k on it .today is mod day so thanks for the tip.
Waldo AZXC VP

Yeah, a note to those who may come across this thread while searching for P0455:

If you get this code, check your gas cap first!

The canister/valve stuff discussed here only applies if you get P0455 repeatedly and have ruled out loose or defective gas cap (which is the more common cause).

what does code 1446 reply to? i thought it was dealing with that vent control valve and the carbon canister below the gas fill up area?

That code means "EVAP Canister Vent Control Valve (Closed)".

The problem we're discussing here is the valve being stuck open. Actually, P0455 is a non specific pressure drop. It just turns out the valve commonly sticks open and causes the pressure drop.

thanks for explaining the code. to remove the actual valve, you simply turn it counter clock wise-it will turn untill a plastic stopper stops the valve from turning and you pull out gently. i must admit that i am almost sure you turn it counter clock wise very gently and once it stops you pull outwards. i am confused about that 1446, i am getting that code 2 to 3 times per weeek. anyhow....i am still happy with my xterra.

SR, here's some info from the service manual regarding P1446

P1446
1446
EVAP canister vent control
valve close

EVAP canister vent control valve remains
closed under specified driving conditions.

Possible Causes:


EVAP canister vent control valve

EVAP control system pressure sensor
and the circuit

Blocked rubber tube to EVAP canister
vent control valve

EVAP canister is saturated with water

Being a Mass-hole has just paid off.

Did some more research, found that in Massachusetts, for 2005 Xterra's that failed inspection due to OBD codes, 100% are from the Evap Control System failures.

Also, I found Mass follows California emissions regs, and all repairs related to smog test failures are covered for 3 years/50,000 miles. (it's right in the warranty book that came with my X!)

I have 48,300 miles, and I'm 3 weeks away from the 3 year mark on delivery date, and due for inspection this month.

So, as soon as that P0455 comes back, I'm going to the dealer to have them do the inspection. It'll fail, and they'll have to fix it under warranty.

Damn - just reset it a few days ago, should be back any time now...

After waiting 10 weeks for the dealership to order the required parts, they finally performed the TSB for the DTC P0455. Replaced the EVAP Vent Control S/V and installed the filter kit.
Free of charge, and I have 32000 miles.
I will post a picture of how it all looks underneath.

Good thing you caught it before 36000 miles.
I’m doing battle with NissanUSA right now. Well, not really “battle”, it’s all very civil at the moment.

My truck qualifies for California Vehicle Emission Control Warranties as laid out on page 10 of the warranty manual (50 state/california emissions equipped vehicle sold in Massachusetts etc) , so any “emission-related part” or anything needed to get the thing to pass the smog test, is covered for 3 years/50000 miles (I just made it!).

However, the dealer won’t cover it and wants to charge about $400 because their computer shows those parts as 36000 mile warrantee.
So, the emissions system and ALL parts related to it are covered for 50000 miles, per the manual, and possibly mass state law. But the parts I need (which are part of said system) aren’t covered???

Sounds like someone punched in “36000” miles into the computer for some parts that should have a “50000 for 50 State/California Emissions” foot note.

I called Nissan USA, reviewed the warrantee, they guy kept saying, “well, maybe it not covered because of this…” No, see the foot note. “Oh yeah, you’re right” yada yada yada. So, they guy finally seems to agree with me but doesn’t have the power to do anything. He’s referring this to the regional rep who’s suppose to contact me within a few days.

I’m fighting this all the way. The written warrantee clearly states ANY EMMISSION RELATED PART, and they acknowledge this is a failure of the emission system and is therefore covered, but they won’t cover it??? This would be comical if there weren’t $400 at stake!

This is the second time I’ve ran into conflicts between their computer system and reality. First time around was the hitch recall – they claimed mine was not part of the recall and even did the WRONG work, leaving me with a defective hitch – they finally corrected the “mistake” and put on a good hitch after I called ‘em on it, but that’s a whole other story/rant which is buried somewhere in the XOC archives.

I like the people at this dealership, and they generally know what they are doing.
But as soon as they look at the "computer", well everything gets all f’d up.