What does the code "P0456 - Evap system (very small leak)" mean?

Hey there,

My 2014 Summit has around 62,000 miles on it. The check engine light came on yesterday, and I found out today that the code is P0456 - evap system (very small leak). The guy at O’Reilly’s gave me a ten-page printout on this code and its possible causes. It seems like the most common (and cheapest) cause is the gas cap. But, I have a capless tank, so that doesn’t apply.

My filler neck door has always been slightly open, and I’m wondering if that could be causing the issue. It seems like getting a mechanic to do a smoke test is the sure way to find out, but with the holidays, it might take a while before I can get an appointment.

Has anyone else experienced this error?

That code,

P0456, is like a cryptic message from your car’s computer. But no worries, I can help you crack the code! P0456 stands for “Evaporative Emissions System (EVAP) Small Leak Detected.” Here’s what that means in plain English:

Evaporative Emissions System (EVAP): This system is designed to prevent gasoline vapours from escaping your car and polluting the air. It captures any gas vapours from the fuel tank and sends them back to the engine to be burned.

Small Leak Detected: The P0456 code indicates that the car’s computer has detected a tiny leak somewhere in the EVAP system. This leak is allowing some gasoline vapours to escape, which isn’t good for the environment or your gas mileage.

What Could Be Causing the Leak?

There are a few common culprits for a P0456 code:

Loose or Faulty Gas Cap: The gas cap is the first place to check. A loose or damaged cap can easily cause a small leak.

EVAP Hose or Line Crack: Hoses and lines throughout the EVAP system can crack or become brittle over time, allowing vapours to escape.

Faulty Charcoal Canister: The charcoal canister is a key part of the EVAP system, and it can become clogged or malfunction, leading to a leak.

What Should You Do?

If you see a P0456 code, don’t panic! Here are some steps you can take:

Check the Gas Cap: Make sure it’s on tight and secure! A simple fix can sometimes solve the problem.

Take it to a Mechanic: If tightening the gas cap doesn’t do the trick, it’s best to take your car to a trusted mechanic. They can diagnose the source of the leak and repair it properly.

A P0456 code is a warning sign that your car’s EVAP system has a small leak. It’s important to address it to avoid harming the environment and potentially hurting your gas mileage. By checking the gas cap first and then consulting a mechanic if needed, you can get your car back to running clean and efficiently.

Hey there! Based on my experience with a similar issue almost 10 years ago (so details are a bit fuzzy), my old TJ threw a code like yours, and it turned out to be a tiny crack in one of the vacuum lines under the hood. I’d suggest checking the small hoses on the driver’s side near the firewall.

I had a similar issue under the hood. Duct tape fixed for me.

Might be your purge valve. It’s a common failure but cheap to replace.