Car Problem - 2010 Nissan Sentra code; P0456

Im going to be going to LA, Cali on the 10th and I went to Walmart on 05/30/2021 (I know a big mistake but my dad convinced me. I’m a girl and have been learning a lot about cars cause of my own car troubles but I still am pretty clueless.) I got a oil change, my tire pressure checked, and my engine air filter changed. Everything was fine until 2 days later.

Here is when my current trouble starts.

I went to the gym in the morning and my car was fine, tire pressure light was on as always, everything normal. Later the day, my family and I go to Denny’s and I notice that my “Engine Service Soon/check” light is on and I just think “WHAT THE F&$K IS THE PROBLEM NOW!”. After Denny’s, I head back to Walmart to see if they can look over it as part of the “contract” car release forms you sign states that if you have a problem after a service with them, you can go back to get it looked it, as long as you don’t go to another shop after your Walmart visit as they will no longer be responsible. I go there and they tell me that they can’t help me because they don’t do diagnostics but I argue but they shut me down.

I went to O’Reilly’s across the street to borrow the code scanner and I got the code P0456 - “Evaporative Emission System, Leak Detected (very small peak)”. The guy at the front desk tells me he can check my engine for me real quick and he looks over it and notices my filter box.

He tells me I’m missing a clip for my air filter (My box has 2 that keeps it closed) and that that’s the reason for the code as there is a gap that air is getting in/out. I look over and I see that I am missing a clip and it all clicks together.

Those Walmart Bas*ards!

The form I got back had a technician comment that says “1 air box clip missing”. The thing is, I’ve never had this problem/code before and I remember having and checking for both clips after my uncle was done with the engine service and I’ve never touched the filter box before. It seems to me that they lost it and didn’t want to replace it or be responsible and decided to claim that it was “missing” (I feel so stupid for not taking a picture before leaving it).

I didn’t think think much of the technician comment beforehand as I looked up how a missing air filter clip can affect your car and I saw one comment to just forget about it. To not be worried, I forgot about it (my mistake I know). Now, 2 days later after the 30th, I find out about the code and go home. I decided not to drive my car until I get a new clip as I know that one’s air filter is their engine first line of defense and should be protected.

I order a new clip on Amazon that should arrive tomorrow, but I am worried that once I put the clip and reset the code, the light will come on again.

I know there could be other causes such as a fault gas cap, Evap system Hose, Vapor Canister, Purger Valve, etc…

I have checked my gas cap and it’s fine, it’s a new gas cap I bought after I had replaced the old one it previously had. I have no idea how to change my evap hose or Valve, ive looked up videos on how simple and easy it is to do it at home, but I do not want to do it myself due to fear Of messing it up and I don’t want to bother my uncle about it.

Do you guys think it’s because of my missing air clip? Or could it likely be the other possibilities?

I’ll update!

Thank you for reading!

its possible the lost the clip and put the filter box back so it made a good seal for a day or so until you hit a big enough bump to crack the seal and cause the code. put the clip on when you get it. it will take usually anywhere from 50-100 miles to reset the computer. I would get the tire pressure light checked out. you might have a small nail or something in your tire causing you to loose air. you dont want to have a flat in the middle of nowhere on your trip.


Thank you so much! My tire pressure light has been on ever since I’ve gotten the used car and I’ve checked the tire pressure and they are at 34 PSI each and are fine.

then its probably one of the tps sensors in the tire that needs changing. setting of the light. have a safe trip.

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Thank you, have a nice day!!!

I don’t think that evap system code is going to have anything to do with the air filter clip.

Running the engine with that code isn’t going to hurt anything either, btw. However, I would want to repair it if it was me. I hate dash lights.

If you need to use the car before the clip comes in, you could probably just use duct tape to seal any cracks where the lid isn’t sealing against the airbox. Kind of a hack, but all you need is something to temporarily seal the box.


One good thing is that the code could go away by itself. I had that warning once, opened the gas cap and put it back on and the code went away and never came back. Small leak could be a one timer.

Don’t clear codes unless you live where there is no emissions testing. The monitors will not all reset easily.

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That code could also be caused by a loose gas cap. Take it off, make sure the gasket and seating area are clean, and put it back on.

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… and then drive the car for 2 or 3 “drive cycles” before deciding whether this simple fix worked.

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It usually takes a few days for the code to clear. for a loose gas cap.I usually clear the code with my OBD2 scanner when that happens.

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I doubt that the missing clip has anything to do with the code.
Personally, I think that you are being too harsh on Wal Mart. The car is 12 years old and who knows; that clip may have been missing for the past 8 years.

I realize you stated that the clips were not missing and an uncle had a hand in some unspecified engine service. I tend to think that you have never even paid attention to those clips before until it was mentioned by the auto parts guy and that you also will not think highly of me for my comments.


No i agree after some research that the clip is most likely not the issue and it’s with the emission. I had more to my post but I cut it down so it wouldn’t be too long and bore people, but my uncle had serviced my engine and we bought a new engine Nd other parts due to some metal grinding and burning oil. Maybe I shouldn’t be going to hard on them, but I had both clips on my air filter before I went to Walmart. But that’s not really important as it’s an easily replacement part, I’m hoping to go a smog repair shop today and getting it properly diagnosed

Yes I agree that the clip is most likely not the reason for the code haha. I’m taking it to a smog repair shop and seeing what the problem is because while it’s fine to drive, I wouldn’t want the bad fumes (if that’s the problem) to seep out into the environment

Thank you!