P1456Manufacturer-specific code

P1456 Code: EVAP System Leak: Fuel Tank Side (Honda)

On Honda and Acura vehicles, the P1456 code means the EVAP system has a leak on the fuel tank side. It usually causes no noticeable symptoms. A loose or worn gas cap is the most common cause.

Severity
Low
Can I keep driving?
Yes, no immediate risk
Estimated cost
$10 to $400
Difficulty
Easy
System
Emissions Control
Applies to
Depends on the manufacturer

Common in: Honda

Updated Reviewed by Renzo Chacca

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What the P1456 code means

P1456 is a manufacturer-specific code: the 1 in the second position means each automaker defines what it means, not the generic SAE standard. The most widespread definition is the one used by Honda and Acura. If your vehicle is another brand, confirm the code text with a scan tool that supports that manufacturer.

ManufacturerMeaning of P1456
Honda and AcuraEVAP system leak: fuel tank side

Honda tests the EVAP system by closing the vent valve and measuring tank pressure with a cold engine or after shutdown. It splits the test into two parts: the tank side and the canister side.

The computer sets the P1456 code when it detects a leak in the part of the system that runs from the tank to the control valve. The most common cause is the gas cap.

Before you start repairs, confirm the make, model, year and engine. With manufacturer codes, the same number can change even between engines from the same brand.

P1456 code symptoms

  • Check engine light on.
  • Usually no symptoms at all.
  • A fuel smell in some cases.

Likely causes of the P1456 code

  1. Gas cap not fully closed or with a worn seal. The most frequent cause.
  2. Corroded filler neck. Confirm it with the tests in the diagnosis section.
  3. Tank pressure sensor. Confirm it by comparing its reading with the real value.
  4. Tank hoses. Check for cracks and clamps, especially in the hot areas.

How to diagnose the P1456 code step by step

  1. Check and tighten the gas cap until it clicks.
  2. Inspect the gas cap seal for cracks or flattening.
  3. Run a smoke test to find the leak.
  4. Check the tank pressure sensor against the expected reading.

How to fix the P1456 code

  • Replace the gas cap if the seal is worn.
  • Repair the leak the smoke test points to.
  • Clear the code and complete a drive cycle.

Technical reference data

  • The test needs the tank between one quarter and three quarters full.
  • P1xxx codes are manufacturer-specific: confirm the definition with a scan tool that supports your brand.
  • Reference values: check the manufacturer data for your vehicle.

Brand-specific notes

Start with the cap. It is the cheapest thing to check and the most likely culprit on these vehicles.

P1456 on Honda

Very common on the Civic, Accord, CR-V, Fit and Odyssey.

If your vehicle is another brand, check the table above for the meaning its manufacturer gives this code and confirm it with a compatible scan tool.

Frequently asked questions about P1456

What does the P1456 code mean on a Honda?
It means there is a leak in the EVAP system on the fuel tank side. It usually causes no symptoms.
Does P1456 mean the same thing on every brand?
No. It is a manufacturer-specific code, so on other brands it may not exist or may mean something different. Confirm it with a scan tool that supports your make.
Can I drive with a P1456 code?
Yes. A P1456 code does not affect how the car drives. You should still repair the leak to pass an emissions test.
Is changing the gas cap enough?
In many cases, yes. The cap is the most frequent cause. If the code returns, run a smoke test to look for other leaks.
How much does it cost to fix P1456?
Roughly $10 to $400 on a Honda. A new gas cap sits at the bottom of that range, and a hose or neck repair costs more.
Will a P1456 code clear itself?
Sometimes, if the cause was a cap that was not tightened and you fix it. The light turns off after the system passes its test over a few drive cycles.

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Questions about the P1456 code

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