2 quick things, 05 Pathfinder...I see that P0455 is some sort of vac issue in the evap/emission control system. After getting the new $42 Nissan gas cap, it still threw the code after about 260 miles. What is the next most likely culprit after the cap please? I see in the serv manual there are several valves, and the lines all look good to me. Just wondering what is the next thing to try, or should I just let the dealer rob me to run the tests on valves, etc. to find the one that is bad ?

#2, as I was looking at the lines etc, and removed the top engine cover and the main air intake unit (attached to the air cleaner box to the mass flow unit) , I noticed a rubber hose/line that is attached to the back side (side facing the firewall) and it makes a 90 degree bend and then it has a reducing/connector type insert and then NOTHING, just hanging in the air. Looks like the other end goes down and into the trani (?), so it could be a breather tube or something, but seems strange to be hanging there with an open end & never noticed it before....should this be attached to some other pipe/tube, and if so could this be part of the P0455 code issue above ? I have tried to attach a picture of it....the hose with the 90 degree bend, white paint mark on it is the one, and attached on a small plastic tab/clamp near the corner of the air cleaner box closest to the engine & oil dip stick. WHAT IS THIS ? SHOULD IT BE CONNECTED TO SOMETHING ELSE ? See picture at http://i228.photobucket.com/albums/ee28 ... aner-1.jpg ( I hope).

Thanks,
FRD

That's a vent hose in your pic and no, it's not supposed to be hooked up to anything. P0455 is a code for a large leak in the evaporative emissions system, the system that used the charcoal canister to store fuel tank vapors until they can be later introduced to the intake manifold and burned in the combustion chambers. This prevents fuel vapors from escaping into the atmosphere. The vehicle uses a self-check system to make sure it is working properly. A loose or improperly installed gas cap is often a cause for an evap leak code. A faulty vent in the gas cap can cause the code, but it is relatively rare in Nissans. Many gas caps are unnecessarily replaced because of this. The best way to check for leaks is with a "smoke machine" and a scantool, but you usually only find these in dealers and well equipped shops as the smoke machine runs several thousand dollars. There are a number of componants in the evap system. Major players are the charcoal canister, the vent control valve (which bolts on to the back of the canister), the purge valve, which opens to allow the vacuum from the intake manifold to pull the vapors into the engine, and the evap pressure sensor, which is the "eyes" of the system for the ECM. There could also be a few miscellaneous valves, but those are the main ones. If all of the vacuum hoses are connected and not leaking anywhere, the vent control valve is the most common cause for a leak code. It is normally "open," but "closed" by the ECM when needed to for testing purposes of the evap system. These valves can stick open, which will show up as a leak. That said, to simply replace the vent control valve without testing the system is just guessing. One can't say it is the problem or not unless confirming it as faulty by performing the diagnostic tests in the FSM for the trouble code retrieved.

Agree with SMJ on the diagnosis.

I have seen my fair share of Nissans (including mine!) that exhibit either P0455 or P1446, or sometimes both. It seems there is a weakness in the design of the vent control system, which has been updated by Nissan in the last couple years.

Another symptom I have is that I can't top off my fuel tank. When its full, its full! Can't even get another $0.25 in there, it just spills out.

t

OK, I have been reading around and see the valve you guys are talking about has lots of issues and seems to be the likely part that needs replacing. Now I find another TSB about the part having a new style, and not sure if it should also get the filter or not from the other TSB ? The TSB mentioned most showing the new filter is this > http://engine-codes.com/uploads/nissan/NTB07-060a.pdf <which> http://www.jdmgallery.com/wp-content/up ... CEMENT.pdf < which mentions the new type/looking valve. I see both types are still sold by the various sources. Is the newer type the way to go ? Is the filter really necessary, or maybe the newer type does not need the filter ? Is the OE type worth the extra ~ $50 or so (thru everythingnissan, or where?) vs. the knockoffs ? Thanks for all the great help !

If it were me, I would install the filter kit assy. per NTB07-060a, but substitute the update vent control valve per NTB09-129. I'd be surprised if Nissan hasn't superceded the old vent control valve P/N with the new one. As far as the aftermarket options, it would be hard to tell if they had the improvements of the updated vent control valve. It's always best to install the "latest and greatest" parts when available. For prices, check out 1stAAANissanParts.com.

Damnit. I've been getting the same code. Replaced my fuel cap as well and it's still not going away. Was just about to post up about it but it seems that's been done for me.

Now to find out where it's leaking from

OK, spent the $100, ordered the part and should get it in next week. Trying to get the old one out today and see if it has a broken spring or can be cleaned out. Will keep ya posted...thanks to the experts for all of the help and PM, you guys are great. Will let ya know if the new valve kills the SES light.

FRD wrote:OK, spent the $100, ordered the part and should get it in next week. Trying to get the old one out today and see if it has a broken spring or can be cleaned out. Will keep ya posted...thanks to the experts for all of the help and PM, you guys are great. Will let ya know if the new valve kills the SES light.

Any updates?

Did you replace the valve? The Filter Canister? Both?

I did put in a new control valve and have ~ 800 miles now with no SES light. I got the newer/newest (?) version of the valve that has a metal housing around the one end, and looks a bit different than the original and other versions of the valve. Fits in just the same, and again the hardest part is just getting the valve out of the canister....just have to twist it just right to allow it to pop out, and not the easiest thing to get upward force on it up in that small space for your hand. There was no filter recommended with the new valve, so I did not go to that trouble.

Anyways, not sure a new gas cap was ever needed, but as a cheaper and easier first attempt I would probably do it that way again. Once the light and code came back, as the experts said the control valve is the next most likely problem. Replacing it worked for me...thanks again.

FRD

I've seen a lot more vent control valves fail than gas caps!

Part arrived! Got it for 75 bucks off ebay. Looks like a genuine, brand new part, still sealed up. Gonna try & get it in there today. Will post results after a few days of driving.