P0456 on Subaru
Evaporative Emission Control System Leak Detected (Very Small Leak)
P0456 on Subaru vehicles indicates evaporative emission control system leak detected (very small leak). Au7o has documented this code across 1 Subaru model — most commonly on WRX. This emissions code means the evaporative emission (EVAP) control system has detected a very small leak — even tinier than the one flagged by P0442, roughly equivalent to a 0.020-inch hole. The EVAP system traps fuel vapors from the tank and prevents them from escaping into the atmosphere, and the computer tests for leaks by sealing the system and watching for pressure or vacuum loss. Because the leak is so small, the cause is often subtle, but a loose or worn gas cap is still the most common and easiest to check. It generally indicates a minor seal, hose, or valve leak somewhere in the fuel vapor system. Typical repair costs on Subaru range from $300 to $900, depending on the specific model and root cause.
Common Causes of P0456
- •Loose, worn, or faulty gas cap or cap seal
- •Cracked or loose EVAP hose or line
- •Leaking vent valve or purge valve not sealing
- •Damaged O-ring or seal at the fuel filler neck
- •Small crack or leak in the charcoal canister
- •Leaking fuel tank or sending unit gasket
- •Loose or corroded EVAP component connection
P0456 on Subaru by Model
Subaru WRX(1 issue)
- Fuel Filler Neck Corrosion Causing EVAP Leaks, Fuel Smell, and Check-Engine Light2002-2007
Rust-belt GD-chassis WRX models are known for corrosion of the steel fuel filler neck and vent tubes behind the left rear wheel area. As the neck rusts through, owners notice a raw fuel smell, difficulty filling the tank, or EVAP leak codes from the compromised venting system. Subaru issued recalls and service campaigns on related Impreza models in salt-belt states because the corrosion could lead to fuel leakage.
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What does P0456 mean on Subaru?▼
P0456 stands for "Evaporative Emission Control System Leak Detected (Very Small Leak)." This emissions code means the evaporative emission (EVAP) control system has detected a very small leak — even tinier than the one flagged by P0442, roughly equivalent to a 0.020-inch hole. The EVAP system traps fuel vapors from the tank and prevents them from escaping into the atmosphere, and the computer tests for leaks by sealing the system and watching for pressure or vacuum loss. Because the leak is so small, the cause is often subtle, but a loose or worn gas cap is still the most common and easiest to check. It generally indicates a minor seal, hose, or valve leak somewhere in the fuel vapor system. On Subaru specifically, this code is documented across 1 model.
What causes P0456 on Subaru vehicles?▼
Common causes on Subaru: Loose, worn, or faulty gas cap or cap seal, Cracked or loose EVAP hose or line, Leaking vent valve or purge valve not sealing, Damaged O-ring or seal at the fuel filler neck, Small crack or leak in the charcoal canister. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0456 on a Subaru?▼
Repair costs on Subaru range from $300 to $900, depending on the specific model and root cause.
Which Subaru models have P0456 documented?▼
Au7o has documented P0456 on 1 Subaru model: WRX.