# Codee P0455 (Large Evap. System Leak)



## slhaas (May 1, 2005)

For the last week and a half I've had a "Service Engine Soon" light come on and off. It was on when I was driving out of town for 4 days and then when I got home and was about to take it in, it went off... for another 4 days... then yesterday it came back on. I had the code pulled and it came back as P0455, Evaporative System Leak - Large. I have no idea where to begin diagnosing this. What hoses should I check, what should I look for and where is the canister? From what I found it seems that the problem is usually there or the gas cap. Is there anything simple to check or process of following some lines to get to the cause of this? I checked the gas cap and it seemed tight, but I also put some fuel system cleaner in the car, and made sure that the cap was replaced tightly. The code was turned off when it was pulled, and it hasn't yet come back, but I need to know what to look for if/when it does come back.

Thanks in advance

2004 Sentra 1.8s with 39,000 miles FYI


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## Sorority Demon (Jul 15, 2005)

One option you could do is hook up some compressed air into your fuel system, preferably nitrogen because it is an inert gas and wont cause an explosion. If you have a leak somewhere you should hear an air leak somewhere. To pin point it use a hose and stick one end to your ear and move the other end around until you clearly hear where the leak is.


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## metro273 (Sep 16, 2005)

Alot of times the vent control valve, attached to the evap canister, sticks "open", causing the code you have. We, at the Nissan dealership I work at, replace both items cause the 2 10mm bolts seize up inside of the canister and when they are removed, the canister cracks. That's usually where the problem is at...Good Luck!


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## slhaas (May 1, 2005)

Where is the canister, and where is the valve... what do they look like? Is there a way to discern if that is indeed the problem (a visual test or something I can do to verify this). Is this a relatively simple job that I can do myself?


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## metro273 (Sep 16, 2005)

slhaas said:


> Where is the canister, and where is the valve... what do they look like? Is there a way to discern if that is indeed the problem (a visual test or something I can do to verify this). Is this a relatively simple job that I can do myself?


The canister and valve are attached together. They are underneath a plastic cover, behind the left rear tire. You need to pressurize the EVAP system, with light compressed air and spray soapy water around the valve. In most cases, the leak will be found right away cause of the soapy water making bubbles. 
One note: the vent control valve, attached to the charcoal canister, must be energized(closed) for the bubbles to show.


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## slhaas (May 1, 2005)

Am I looking for a fuel, vapor or vaccuum leak? I felt around under there and didnt notice any obvious cracks/holes and no moisture or dirt. It also SEEMS that the light comes on when my fuel gets low, but I'm not certain of this yet because it's what I remember, and I haven't actually tested it yet. What should I be concerned with regarding this issue? Im supposed to drive 1500 miles next weekend. The car doesn't seem to be acting any differently, but am I at risk of a fire or damaging the engine or something, or perhaps a fuel economy loss?


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## goatty9 (Jun 2, 2005)

slhaas said:


> Am I looking for a fuel, vapor or vaccuum leak? I felt around under there and didnt notice any obvious cracks/holes and no moisture or dirt. It also SEEMS that the light comes on when my fuel gets low, but I'm not certain of this yet because it's what I remember, and I haven't actually tested it yet. What should I be concerned with regarding this issue? Im supposed to drive 1500 miles next weekend. The car doesn't seem to be acting any differently, but am I at risk of a fire or damaging the engine or something, or perhaps a fuel economy loss?



I have 1441 code on mine for about 6 months. It is the same problem as above the vent control valve. 

As ask before, is there any thing I should know be for I change this part? Ie tricks. 
As for the cost the part at a dealer in Ontario is about $120 CDN. I tried the scrap yard they want $30 but will not warrat the part becuase they can not be tested before they are sold. Does any body else know any where I can get this part cheaper then $120?


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