Modern cars are all about optimizing performance, fuel economy, and maintenance costs, but most importantly, emissions.

Environmental safety and emissions have been a big part of the automotive industry for several decades now. Emissions’ standards have made cars complicated in the sense that modern cars are full of sensors and devices whose sole purpose is to limit said emissions.

All these components and relevant sensors, even though they don’t necessarily affect the way the car handles or performs, need to be in good condition for the engine to work properly. Not only that, but you’ll often find them triggering check engine light codes when they fail.

In this article, we’ll be going over one such check engine code — P0456. We’ll talk about what it means, what causes the P0456 code to pop up, its symptoms, and how to fix it.

What is the P0456 Code, and What Does It Mean?

The P0456 fault code stands for ‘evaporative emission control system leak.’ What this means is that fuel vapors are escaping into the atmosphere and that your car has increased emissions.

The check engine light will light up on your dash due to the P0456 fault code if there are two failed leak tests in a row. Your car automatically checks for leaks in the evaporative emission control system every time you turn off the car and if there’s not enough pressure in the system, the code will be stored in the ECU.

Modern cars have evaporative emissions control (EVAP) systems, which will trigger a P0456 engine code if they’re reading values that are out of spec. EVAP systems use things such as leak detection pumps to scan the entire EVAP system for leaks. Once a leak is detected, you’ll get that bright yellow (or orange) check engine light on the dash.

That being said, this fault code is a low severity engine code, so it won’t affect the way your car is driving. However, because it triggers the check engine light, you shouldn’t ignore it for too long. If nothing else, it can mask other CEL codes which can be quite dangerous for your engine.

What Causes the P0456 Fault Code?

When it comes to the P0456 code, thankfully, there aren’t many things that can cause this code to pop up in the ECM.

The first and most common cause for the P0456 fault code is a disconnected hose or a crack in the evaporative emissions system. To trigger the P0456 code, the leak doesn’t need to be large, but just enough to alter the pressure in the system. It can be a hairline crack in the evaporation hose or a faulty connection between the hose and the system.

A cracked fuel tank will also cause the check engine light to come up on the dash. This also applies to cracked or disconnected fuel hoses. Another common cause for the P0456 engine fault code is a faulty purge volume control valve.

Can P0456 Be Caused By a Faulty Fuel Cap?

Yes, a faulty fuel cap can cause trigger the P0456 error. Some vehicles are fitted with sensors that can read whether or not the gas cap is fitted properly. If the fuel cap isn’t forming a proper seal for any reason, you will most likely see a CEL light up on your dash.

If you find the P0456 fault code to be the reason for the check engine light to come up, it’s best to replace the fuel cap as soon as possible. We recommend that you use an OEM fuel cap as well. Cheap aftermarket ones are very unlikely to meet the emissions norms of your car’s manufacturer, which will only lead to more fuel cap-related CELs.

What Are the Common Symptoms of P0456 Fault Code?

There are only a couple of symptoms that are specific to the P0456 code. The first one is the illuminated check engine light. Although it doesn’t pinpoint the P0456 fault code, it tells the driver that there’s an issue with the car, and by using an OBD II scanner, you’ll be able to read the code that’s stored in the ECU.

With that said, the only somewhat dangerous symptom this code can cause is the smell of fuel inside the cabin. There are a handful of issues that cause the smell of fuel to be present in the cabin, and the P0456 code is one of them.

Increased vehicle emissions are also one of the common symptoms of this code. Even though you probably won’t notice it on your own, the moment you take your car for an emissions test, you’ll know that something is wrong.

Last, but not least, you’ll notice the fuel economy getting worse.

None of these symptoms seem like there’s something seriously wrong with the car, but avoiding addressing them can cause additional problems so fixing the issue as soon as possible is always recommended.

How to Diagnose the Cause of P0456 Code

When it comes to diagnosing the P0456 fault code, the first thing you’ll want to do is scan your car with an OBD II scanner and make sure that this code is the only one showing up in the ECU. Other fault codes can be an underlying issue that causes similar symptoms so before taking any action, make sure it’s the only fault code stored in the ECU.

After confirming that the P0456 fault code is the only one causing the check engine light to come up, you can start by inspecting the fuel cap for damage and fitment. If you notice any kind of damage on the fuel cap, or if it’s not fitting properly, replace the fuel cap with a new OEM one. Clear the code from the ECU and test the car to see whether the issue comes up again, continue with the diagnostic process.

Diagnosing the P0456 code further will require knowledge about the whereabouts of relevant components. You’ll also need to lift the car to check whether the hoses and the fuel tank have any cracks and leaks. If you don’t have the space or the equipment to safely lift your car and check underneath, it’s best to leave this test to your local mechanic.

Because the leak is usually too small to see, a smoke test may be required to find the exact part that’s causing the P0456 code. It’s also the most accurate test, so if you can’t find the cause on your own, it’s the way to avoid costly and long-lasting diagnostic procedures.

Can You Drive with P0456 Code, and For How Long?

The P0456 generic fault code is considered low on the severity scale, so driving your car is safe, but you’ll need to address the issue as soon as possible to avoid decreased fuel economy and increased emissions.

Implementing a Fix

Even though some cars can throw the P0456 code, not all cars will. If you find the P0456 fault code stored in your car’s ECU, there are a couple of fixes that will get your car back to optimum performance.

The simplest and most inexpensive fix is replacing the fuel cap. This code is caused by a small leak, and it can be from the fuel cap if it’s cracked or doesn’t fit properly. Depending on the model of the car, replacement OEM fuel caps can cost anywhere from $20 to around $60, depending on what you drive.

Replacing cracked hoses can also fix the issue. Using OEM hoses in the evaporative emissions system will give you peace of mind knowing that your chances of dealing with the same issue are close to none. So many quality control processes are involved in making an OEM part, which is why OEM parts are often more expensive than aftermarket, but still cheaper than Genuine. The differences between OEM, Genuine and aftermarket are important, to say the least. If you’re not sure which route to go, Genuine or OEM is a safe bet.

Another common fix for the P0456 code is replacing the canister purge valve. If you don’t know where it’s located in your car, check your users’ manual. It’s usually found somewhere on the back of the engine, facing the passenger cabin.

Replacing the entire fuel tank is a viable solution, but one that is very rarely applied in these types of scenarios. If you’ve tried everything else, and you’re still having the same CEL fault code popping up, by all means, inspect the fuel tank. Modern fuel tanks are made of High-Density Polyethylene or HDPE. In other words, they’re made of plastics. While they very rarely crack, it does happen.

Use Only OEM Parts To Prevent The Same Issue from Happening Again

Although this code doesn’t appear very often, it can be an irritating one because it doesn’t trigger many symptoms, and it’s not that easy to diagnose.

Even though more affordable alternatives will fix the issue, it’s important to remember that the EVAP system is fairly sensitive. Because of that, it’s highly recommended that you use only Genuine, OEM, or high-quality aftermarket parts to fix any EVAP system-related issues. We at eEuroparts.com offer a wide selection of everything mentioned above for almost any European vehicle.

Whether it’s a fuel cap or valve, we’ll help you find quality parts that will keep your car in perfect shape!