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Mike V.
Mike V., Nissan Technician
Category: Nissan
Satisfied Customers: 25342
Experience:  Nissan factory trained and Certified Subaru Technician.
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2003 nissan pathfinder. ck engine light. code p1456. i changed

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2003 nissan pathfinder. ck engine light. code p1456. i changed the gas cap. did not work. when i open the gas cap i hear pressure. i have to resolve this for state inspection.

GreetingsCustomerand welcome to JA! I will do my very best to assist you with your problem.

Are there any other codes with this one? Also, do you have any trouble filling the tank?

Customer: replied 7 years ago.
no other codes. the vehicle has 70k miles. no problem filling the tank. but i have had one incident where after i filled up and got back on the road it seemed as if air was in the gas line. it cleared up itself. the ck engine light has gone off and on a few times. it does seem to be associated with fuel.

Ok, the P1456 code is a catch all code for a small evap leak. What we normally see on these is the O ring leaking where the vent control valve is bolted to the charcoal canister. You may actually have to have the evap system smoke tested to determine the area of the leak and then determine if you can do the repair yourself. I can only tell you the most common place that I see this occur. Here is a diagram of the vent control valve in case you want to try and replace it on your own. It does come with a new rubber O ring.


Customer: replied 7 years ago.
i do all my repairs no problem. when i open my gas cap i hear air. is this a vacuum or pressure. if the ring was leaking wouldn't it equalize?

Well, that doesn't match the code, so I figured it would be best to resolve the code and see if that goes away as well. This code is for an evap leak the size of a pin hole.Basically .5mm.

The vent valve should open when the purge valve opens and sucks the vapors out of the canister. If it is not opening all the way,then you might get that sound

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