Is your Check Engine Light on? Are you getting a P0456 error code from an OBDII reader in your vehicle? This is a fairly common problem with Toyota Camrys, and luckily is has a pretty easy fix. This article addresses some of the most common causes of this error, and more importantly, how to fix them!

What Does P0456 Mean?


First of all, you can use an inexpensive OBD2 scanner to read and reset your the error code(s) whenever your “Check Engine Light” comes on. The error code P0456 refers to the following:

P0456 – Small Leak Detected in Evaporative Emissions System

This means that the ECM (car’s on-board computer) has detected a vapor leak in the evaporation system. The leak is small, smaller than 0.020 inches, but it means that gas vapors are escaping.

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Most Common Cause of P0456 Error

Over the years I have had the following error code periodically: P0456, and the reason has typically been that the gas tank cannot hold a vacuum: it has a leak somewhere. In the vast majority of cases, the leak occurs around the gas cap seal. Either the rubber seal in the gas cap is bad or the lip of the gas tank that the gas cap seals against is rusty causing a poor seal.

The easiest way to deal with this problem is to buy a new gas cap. The dealership will charge around $65 for a new one. You can get the OEM replacement for 1/4th the price on Amazon. This gas cap also fits the Highlander, Tacoma, Sienna, Scion and RAV4. The gas cap part numbers by year are listed below.

The seals on gas caps tend to go bad after 5-10 years it seems. When I replaced my gas cap, the check engine light (CEL) went off (you will have to wait for about 1 tank fill-up before the CEL will turn off, unless you reset the CEL with a error code scanner.

Other Causes of P0456

The other problem can be a rusty or corroded gas tank lip, so that even if you have a new gas cap, it still can’t make a nice seal. In this case, it is just a matter of cleaning the rust off. I also had that problem recently.

This is the ‘before’ photo of the gas cap. Notice the rust and corrosion around the rim. Clearly it needs some cleaning…!


Here is an especially bad spot of rust, very likely the source of the leak…


Use a file to scrape off the rust.


Once it is cleaned off, put a little rust inhibitor on there, for example, I used this silicone spray.


Wipe off the rust you have filed off, and apply the silicone to the rim.

Also clean the rubber seal on the gas cap.

This is a photo after everything has been cleaned.


Replace the gas cap.


After driving for ~ 500 miles, the P0456 error code has not returned!

If you determine that your gas cap is bad and needs to be replaced, here are links to the correct parts on Amazon:

Thanks for reading, and I hope this was helpful!