Home > OBD2 Codes P0456 Engine Code | Evaporative Emission Control System—Small Leak Detected
The DTC P0456 signals a small leak in the evaporative emission control (EVAP) system. Possible causes: faulty gas cap, defective charcoal canister, bad purge or vent valve, or damaged EVAP line. Cost: $20–$507, depending on the problem. The problem is most likely with Toyota, Ram, and Jeep models.
- David Goldberg
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Table of Contents | |
Code P0456 indicates a small leak is detected in the evaporative emission control (EVAP) system. | |
How to Diagnose The Cause of Your P0456 Code | Identify the probable reason for a P0456 code, such as a faulty gas cap, defective charcoal canister, bad purge or vent valve, or damaged EVAP line. |
Can I drive with a P0456 code? | Yes, DTC P0456 is a less serious problem. However, repairs shouldn’t be delayed for very long. |
DIY | How To Fix P0456 Causes | DIYable P0456 triggers include:
|
P0456 Code FAQs | Frequently asked questions:
|
Modern cars with internal combustion engines are all about limiting emissions—a feature managed by sophisticated engineering and federal regulations. Part of this technology involves restricting the amount of fuel vapors that escape into the atmosphere, which falls under the evaporative emission control or “EVAP” system. A diagnostic trouble code (DTC) of P0456:
Evaporative Emission Control System Leak (small) indicates a problem with the EVAP system.
Before getting into the specifics of a P0456 code, let’s explore the essentials of the EVAP system and how it works.
- Fuel Tank: As fuel sits in the tank, it evaporates, creating fuel vapors.
- Charcoal Canister: The EVAP system captures these vapors and stores them in a charcoal canister, which is filled with activated carbon. The carbon absorbs and holds the fuel vapors.
- Purge Control Valve: When the engine is running and certain conditions are met, the engine control module (ECM) opens the purge valve. This allows the engine to draw fresh air through the charcoal canister, pulling the fuel vapors into the engine to be burned during combustion.
- Vent Control Valve: The EVAP system also has a vent valve that allows fresh air to enter the charcoal canister when the purge valve is open to draw the fuel vapors out.
- Leak Detection: The EVAP system is designed to be a closed arrangement. If there is a leak, the ECM will detect it and trigger a check engine light, including DTC P0456.
If there’s any good news from this situation, it’s that P0456 is a low-priority problem. This doesn’t mean you should ignore the issue. Rather, you can keep driving but should attend to the code in days or weeks, not months. Besides a check engine light, you may notice a modest drop in fuel efficiency or a slight fuel aroma. Otherwise, a P0456 code has little impact on a car’s operations. In addition, this DTC can cause your vehicle to fail an emissions test.
Let’s dive into what code P0456 causes, typical repairs, and the most common vehicles for this problem.
Possible Causes of P0456 & Their Repair Costs
The essence of DTC P0456 is a small leak in the EVAP system, and that’s the challenge. Many small EVAP leaks are difficult to detect, even for professional mechanics with sophisticated tools. In this case, small means an opening less than 0.02 inches in diameter. To put that measurement in perspective, a human hair has a diameter of 0.001 inches. So, it doesn’t take much of a leak for problems to arise.
Check out the FIXD article on the most common causes of check engine lights.
Let’s break down P0456 repairs into likely trouble spots.
P0456 Triggers and Typical Repair Costs
Part To Repair | Part / DIY Price | Mechanic Total Cost |
Replacement gas cap | $20–$60 | N/A |
EVAP Purge Volume Control Valve | $44–$55 | $120–$131 |
Charcoal Canister Vent Control Valve | $50–$65 | $126–$141 |
Replacement EVAP Line | $30–$70 | $106–$146 |
Charcoal Canister | $362–$391 | $453–$507 |
Keep in mind that these are average prices. Some cars may require more expensive parts and additional labor.
Here are more details about the specific parts that can trigger a P0456 code.
Parts Most Likely to Fail & Cause a P0456 Code
Parts that can cause P0456 | How it could cause P0456 |
Replacement gas cap | A loose or defective gas cap allows fuel vapors to escape from the EVAP system. |
EVAP Purge Volume Control Valve | A malfunctioning EVAP purge valve will fail to properly regulate the flow of fuel vapors from the charcoal canister to the engine. |
Charcoal Canister Vent Control Valve | A defective vent control valve can get stuck open, allowing air to enter the EVAP system. |
Replacement EVAP Line | A cracked or broken EVAP line permits fuel vapors to leak out of the system. |
Charcoal Canister | A faulty charcoal canister becomes saturated, damaged, or develops internal leaks, preventing it from properly absorbing and storing fuel vapors. |
Makes Commonly Affected By P0456
While no automaker engineers a car to have known faults, some automobiles fall into predictable trouble areas. In the case of code P0456, FIXD sensor data shows that Toyota vehicles are the most vulnerable, proving that no car is perfect.
Drilling into the details uncovers that the Camry and Corolla, two of Toyota’s best sellers, are at the top of this list. There’s some logic to this, as more cars on the road lead to a greater likelihood of more problems arising. Interestingly, the 4Runner takes the third spot. It’s a popular vehicle but takes a backseat in sales compared to the RAV4 and Highlander, which register at much lower P0456 occurrence rates.
Ford’s worst offender for P0456 codes is the Escape compact crossover, followed by its larger stablemate, the Edge. The Fusion sedan takes third place. Equally interesting is that Ford’s and America’s best-selling vehicle, the F-150, doesn’t show any history with P0456 codes.
Ram doesn’t sell many vehicles beyond its core 1500 pickup. Nonetheless, this truck gets dubious recognition for the frequency of P0456 codes that trigger check engine lights in this model. Ram’s corporate cousin, Jeep, also gets called out for having several models—Grand Cherokee, Wrangler, and Liberty—with dubious P0456 histories.
Nissan completes the P0456 top five brands, making the ‘Hall of Shame.’ The Sentra and Rogue have near-identical occurrence rates among all the vehicles analyzed by the FIXD sensor. Rounding out the company’s unfortunate achievement is the Murano crossover.
Top 5 Makes Affected by P0456 | Most Affected Model(s) | |
Toyota | Camry | |
Corolla | ||
4Runner | ||
Ford | Escape | |
Edge | ||
Fusion | ||
Ram | 1500 | |
Jeep | Grand Cherokee | |
Wrangler | ||
Liberty | ||
Nissan | Sentra | |
Rogue | ||
Murano |
“We only show the top models for the top 5 makes in this article. To see the rest, click on our article about how common P0456 is for all of the top 100 vehicles in the US.”
How to Diagnose The Cause of Your P0456 Code
Because there are thousands of diagnostic trouble codes, you’ll want to use an OBD-II scanner to confirm the source of the problem. Devices like a FIXD plug-in sensor with a smartphone app or a convention unit with a wired connection can almost instantly tell you if code P0456 is the reason for the check engine light.
Depending on how much DIY investigating you want to do, gloves, a flashlight, and a rag could come in handy.
Safety Essentials
Before exploring the source of a P0456 code, you’ll want to observe the following:
- Park on a level surface in a safe area
- Because you may encounter flammable fuel vapors, the car should be outdoors and in a well-ventilated setting.
- Ensure there’s no smoking or other ignition sources nearby
- Perform any visual inspection with the car’s engine turned off
Symptoms of P0456 Causes
EVAP leak detection can be a simple task if it involves a faulty gas cap or fuel filler neck. However, things get more complex beyond these efforts. You’ll notice that some P0456 causes can be investigated by a DIYer, while others may require professional intervention, depending on your experience level.
Click on each Possible Cause of a P0456 code to know the symptoms to look out for and what to inspect.
Symptoms:
- Illuminated check engine light
- Decreased fuel economy
- Fuel aroma
- Increased vehicle emissions
What to Inspect:
Ensure the gas cap is properly seated at the top of the fuel filler neck assembly. It should turn until several clicks are heard.
Symptoms:
- Illuminated check engine light
- Decreased fuel economy
- Fuel aroma
- Increased vehicle emissions
What to Inspect:
Inspect the gas cap for damage, especially along the rubber seal at the base of the cap.Some vehicles (mostly Fords, Hondas, and Chryslers) use a capless fuel filler system. Ensure that the spring-loaded flap and adjacent components are damage-free for these cars.
Symptoms:
- Illuminated check engine light
- Decreased fuel economy
- Fuel aroma
- Increased vehicle emissions
What to Inspect:
Remove the gas cap and inspect the perimeter of the neck, especially where it meets the fuel filler inlet (near the top of the fuel filler assembly). Look for cracks or holes.
Symptoms:
- Illuminated check engine light
- Decreased fuel economy
- Fuel aroma
- Increased vehicle emissions
What to Inspect:
Examine all the EVAP system hoses for cracks, leaks, or other damage. Pay close attention to where the lines connect to the charcoal canister and fuel tank.
Symptoms:
- Illuminated check engine light
- Decreased fuel economy
- Fuel aroma
- Increased vehicle emissions
What to Inspect:
These symptoms are best investigated by a professional technician.
Symptoms:
- Illuminated check engine light
- Decreased fuel economy
- Fuel aroma
- Increased vehicle emissions
What to Inspect:
These symptoms are best investigated by a professional technician.
Symptoms:
- Illuminated check engine light
- Decreased fuel economy
- Fuel aroma
- Increased vehicle emissions
What to Inspect:
Inspect the charcoal canister for damage or leaks. Consult a professional technician for a more thorough diagnosis.
Check to see if any P0456-related technical service bulletins (TSBs) have been issued for your car. This information can often help pinpoint trouble spots with the EVAP system.
Can I drive with Code P0456?
Quick answer: Yes you can continue to drive with the P0456 code
While no check engine light is a “nothing to worry about” event, at least P0456 codes are less worrisome. You can continue to drive with the code and not stress about causing permanent damage to your car. However, this doesn’t mean you have a free pass to ignore the situation. You’ll want to address the problem to ensure maximum fuel economy while minimizing harmful emissions output. Eventually, you’ll need to resolve the trouble if you live in a state with emissions testing. A code P0456 is a sure-fire emissions test failure.
With this in mind, let’s examine what you need to know about driving with a P0456 code.
Causes | Can I Drive? | Risks / Safety / Performance |
Faulty Gas Cap | Yes, but don’t ignore the problem. Get the problem fixed in a few weeks. | Reduced fuel economy, increased emissions, and emissions test failure. |
Damaged EVAP line | Yes, but don’t ignore the problem. Get the problem fixed in a few weeks. | Reduced fuel economy, increased emissions, and emissions test failure. |
Faulty EVAP Purge Volume Control Valve | Yes, but don’t ignore the problem. Get the problem fixed in a few weeks. | Reduced fuel economy, increased emissions, and emissions test failure. |
Defective Charcoal Canister Vent Control Valve | Yes, but don’t ignore the problem. Get the problem fixed in a few weeks. | Reduced fuel economy, increased emissions, and emissions test failure. |
Malfunctioning Charcoal Canister | Yes, but don’t ignore the problem. Get the problem fixed in a few weeks. | Reduced fuel economy, increased emissions, and emissions test failure. |
DIY | How To Fix P0456 Causes
The truth is that there are only a few things a beginner DIYer can do to resolve code P0456. We’ll get into those in a moment. Beyond addressing these issues, resolving a small EVAP system leak requires professional diligence and specialized equipment (e.g., a smoke machine)—elements beyond most novices’ scope. If you have a smoke machine sitting in your garage or workshop, chances are you don’t need to read this article.
Regardless of your skill level, DIY success comes from knowing when to seek professional support as much as it does from completing the task. If your attempts expand the damage, diving too deep into the repair-it-yourself pool can be more expensive than the original repair.
Here’s what a newbie DIYer can handle.
Possible Cause: Faulty Gas Cap
What is it?
The gas cap creates a seal that pressurizes the fuel system. A pressure loss can cause a vapor leak, triggering a P0456 code. All it takes is a misaligned cap that’s not screwed on correctly. However, a damaged or defective cap can lead to the same issue.
How hard is it to fix?
Difficulty Level: Easy
If you can fill your car with fuel, you can ensure the cap is on correctly or install a new one. Just be sure to buy a compatible replacement and avoid getting a cheap knock-off that may not seal correctly. After the fix, you may need to drive a few cycles to reset the check engine light or clear the P0456 code with a scanner like the FIXD app.
Cost of Repairs
Ideally, you won’t have to pay anything if the correction just involves securing the gas cap correctly. Otherwise, a new gas cap costs $20 to $60.
Possible Cause: Defective EVAP line
What is it?
A cracked or damaged EVAP line can disrupt the EVAP system’s operation. Replacing a defective hose can eliminate the leak and resolve the P0456 code.
How hard is it to fix?
Difficulty Level: Moderate
Depending on the car, spotting and replacing a defective hose can be straightforward. It all comes down to access. Someone with moderate skills can swap out a bad line if the part is reachable. This is more so when dealing with a problem in the engine bay than under the car. The axle, suspension, or gas tank can block access. Once a repair is made, you’ll need to wait for the code to clear on its own or use an OBD-II scanner to remove the check engine light.
Cost of Repairs
Expect to pay $30 to $70 for a replacement EVAP line.
Other DIY Considerations for Code P0456
Theoretically, a DIYer with moderate skills can replace a bad purge or vent valve. The same goes for a charcoal canister. However, the challenge is diagnosing that one of these parts is the problem, which is best left to a professional.
P0456 Code FAQs
What makes and models does code P0456 affect the most?
Here’s a breakdown of the vehicles most affected by code P0456, according to FIXD sensor data collected in 2023.
Make | Model | Occurrence Frequency |
Toyota | Camry | High |
Toyota | Corolla | High |
Ram | 1500 | High |
Jeep | Grand Cherokee | High |
Jeep | Wrangler | High |
Toyota | 4Runner | Moderate |
Ford | Escape | Moderate |
Ford | Edge | Moderate |
Ford | Fusion | Moderate |
Jeep | Liberty | Moderate |
Nissan | Sentra | Moderate |
Nissan | Rogue | Moderate |
Nissan | Murano | Moderate |
What BMWs are most likely to encounter a P0456 code?
FIXD sensor data shows that the BMW X5 is more prone to problems with DTC P0456. The 325i is also susceptible. However, the occurrence rate for both models is low compared to popular vehicles like the Toyota Camry and Jeep Wrangler.
How can I prevent P0456 from occurring?
It’s impossible to completely prevent all problems from impacting the EVAP system. However, regular inspections can catch potential issues before a P0456 code gets triggered. For instance, examining EVAP lines can catch damage early before a check engine light comes on.
References:
- Repair-cost estimates, repairpal.com (various dates). Retrieved June 3, 2024, from repairpal.com.
David Goldberg
Dave Goldberg is an automotive journalist and lifelong car fanatic. He writes for numerous enthusiast and business outlets and is an ongoing contributor to HotCars.com, one of the most popular car culture websites. When he’s not writing or driving, Dave is either under a hood or asleep. His credentials include a BA in Journalism from The George Washington University.
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Topics
- Check Engine Light
About the Author
David Goldberg
Dave Goldberg is an automotive journalist and lifelong car fanatic. He writes for numerous enthusiast and business outlets and is an ongoing contributor to HotCars.com, one of the most popular car culture websites. When he’s not writing or driving, Dave is either under a hood or asleep. His credentials include a BA in Journalism from The George Washington University.
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