Got a p0455 code (EVAP Gross Leak)?

[jspe8437]

I got 04 Nissan Sentra and a p0455 code popped up couple days ago. I did try to remove the valve cover for some other issue but was stuck on, but did develop some minor leaks because the valve cover is now a little dirty on top. The 2 hoses that are connected to the valve cover were removed and took out the Variable Valve Timing Solenoid to test it. Don’t know if that has something to do with the code?

So I tested to see if the fuel cap was the problem. I put some vasoline on the fuel cap gasket, clear the code on my scan tool and within 15 miles had the code as pending then about 30 miles the CEL lite up.
Then I tryed a new fuel cap and had (somewhat) better success. I cleared the code drove it 50 miles and noticed my monitors were reset and no codes, so I thought it was fixed. At 95 miles the CEL lite up but then went out at 112 miles. I check my scan tool if the code was gone but it was still there as a DTC, not pending. And now with 285 miles the light came back on. This was in a span of 4 days.

What the next thing I should do to diagnose the code? If I search p0455 nissan on youtube, there’s alot of videos showing how to replace a Canister Vent Valve. How often is something clogged in there, should I do a smoke test and how would I do that, where would I tap into? What’s the most common causes for this code to pop up?

Topic

[James]

If your able to due smoke test that would be best.
Purge valve should be closed at rest. Trying taking off and blowing through if you can. It is bad.
Vent valve should be open at rest but computer will command close in order to test pressure in system, if it to be tested for full closure, you will have to activate that valve with power and ground. Unplug harness, take off valve, activate and try to blow though. Also looking for leaks in hoses, hoses left off etc.
For evap system .

[Dave Tidman]

Do you have a make (assuming Nisan), model, year and mileage? You can smoke test through the evap service port.

Here is a link that talks about the common Nisan issue: http://www.samarins.com/diagnose/p0455.html

Good Luck!

[jspe8437]

dtidman I got a 04 Nissan Sentra 92000 miles. So if I do smoke test it, I’m going to make my own homemade smoke machine like what’s on youtube. you guys ever do that? I know I need a regulator so it can’t go over 2 psi.

Now I don’t have the evap connection adaptor can I unplug the hose on the right side of the green cap test port (in pic) and send the smoke to the back of car. So the vent valve will be open with the car off? The smoke goes threw the whole system, to the gas cap? And how often is there a problem with the Vapor Canister if it doesn’t leak?

Seeing if the purge valve open and closes, I have to take it out and put constant power to it and it will open. Take off the power and it will close? It won’t just pop open and close with a touch of power?
The vent valve is the opposite way, constant power and it will close, release then it will open?

So I take it the minor valve cover leak and 2 hoses connecting to it has nothing to do with this code? See how the left side of the valve cover is dirty now

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[James]

Purge valve is under hood. Take off and try to blow through with it unplugged. If you can it is bad if not put it back on. Next, you can take hose that goes back from purge valve back to gas tank off at purge valve and hook up your homemade smoke machine there.
Your problem will be that your vent valve at gas tank will be open when de-energized and smoke will come through there. For now see if you can plug or cover that and to see if leaking somewhere else in system. If not leaking anywhere else. Try taking vent valve off at gas tank and hook power and ground separate too from car wiring and try to blow through, it should be closed when energized.
Leak is with evap system, not manifold. iF purge valve is closing it will seperate itself from intake when testing. You are looking for larger leak not drizzle while testing. Best of luck.

[Dave Tidman]

In this section of the FSM

http://www.nicoclub.com/manuals/Sentra/2004_Sentra/ec.pdf

The procedure for diagnosing a P0455 starts on page 314.

[jspe8437]

I would like to state a couple things that maybe could pin point the problem.

Since I last posted. The CEL has been on and off. Even on another car I had, it had a p0455 code and it went out in cold weather at times. Is that a common thing with this code?

A couple of us use this car and when filling up we overfill after the pump stops, like rounding off to the nearest dollar or on a long trip putting extra to last further. Heard this could be bad for the vapor canister and or the vapor vent valve?

About once every 3 months or so while trying to pump gas, the pump keeps on stopping like it’s full and the stopping starts a dollar into the fueling of the car. The pump stops 10 times or more. I also heard that this could be more of a vent valve problem or even vapor canister?

Can a clog somewhere pull this code because this code is defined as a (EVAP large leak) If so where most likely be the clog because smoking it out wouldn’t see anything.

Just looking to see the stuff I stated makes it more a part issue vs a leak or just narrow down the issue?

[jspe8437]

So I tested the purge valve, took it out couldn’t blow threw it, put power to it heard clicking and then was able to blow threw it.
Took out the vent valve was able to blow threw, then putting power to it, heard clicking and was not able to blow threw it while powered.
I tested the connectors to see the volts coming out of it. The purge valve connector had 12v and the vent valve had 9.7v, don’t know if that’s enough volts for the vent valve?

I took off the small line (far left) of the vapor canister and the nipple that the hose plugs into was a little shiny and wet and dryed off in 5 mins, looked inside there was nothing clogged that I can see. I tryed taking off the middle bigger connection with a fuel logo on it and I could not take it off. It was a plastic hose with tabs on the side of the connection that needs to be pressed to take off. I’m going to get some hose pliers to see if that might help. What’s the best way to take off those plastic connection hoses? I did blow into the small line of the canister to see if there was anything clogged and seems like that wasn’t a problem.

What’s my next step now? Should I still take off the vapor canister and see if anything comes out of it, etc? The CEL still is on and off every 50 miles or so.

[James]

Your looking for a leak not a clog. The system is detecting a loss when it tries to seal itself and test. And it will be a larger leak. Unsure if that is enough voltage on Vent valve. Next steps would be to check with smoke machine and then possible get specs on vent valve voltage. Probably could find that in FSM listed above. Best of luck.

[Author]

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