A gas cap that isn't sealing perfectly (worn seal or wrong cap). A tiny crack in an EVAP hose or a loose clamp. A slightly leaking purge or vent valve. A small leak at the charcoal canister or filler neck seal.

Trouble codes › P0456

P0456 Evaporative Emission System Leak Detected (Very Small Leak)

Q: What does P0456 mean?

P0456 means the EVAP system has a very small leak, often a gas cap that isn't sealing perfectly. The EVAP self-test found a very small leak, around the size of a 0.020-inch hole, in the system that stores fuel vapor from the tank. It's the most sensitive EVAP test, so tiny leaks that don't affect anything else will set it.

EVAP

P0456 means the EVAP system has a very small leak, often a gas cap that isn't sealing perfectly.

The EVAP self-test found a very small leak, around the size of a 0.020-inch hole, in the system that stores fuel vapor from the tank. It's the most sensitive EVAP test, so tiny leaks that don't affect anything else will set it.

Can I keep driving? Yes, for now.

Safe to drive. It won't affect performance, but it can fail an emissions inspection.

Common causes

A gas cap that isn't sealing perfectly (worn seal or wrong cap)
A tiny crack in an EVAP hose or a loose clamp
A slightly leaking purge or vent valve
A small leak at the charcoal canister or filler neck seal

Symptoms

Check-engine light
Usually nothing else

Common on: Honda Civic, Honda Accord, Honda CR-V, Ram 1500, Jeep Grand Cherokee, Nissan Rogue, Jeep Wrangler, Honda Odyssey, Hyundai Elantra, Dodge Grand Caravan, Honda Pilot, Nissan Sentra, Dodge Durango

What to check first

Replace a worn gas cap with one made for your vehicle; it's the cheapest likely fix.
Clear the code and drive normally for a week; the test needs specific conditions to run.
If it returns, a smoke test is the reliable way to find a leak this small.
Check for service bulletins on your vehicle: some have known EVAP valve or canister problems.

What does P0456 mean on your vehicle?

The likely cause depends on your engine. iRepair researches your exact year, make, model and engine (service bulletins, recalls and owner reports) and tells you what to check first. Your first 3 questions are free.

Ask iRepair about P0456

No scanner? Most auto parts stores read check-engine codes for free.

Related codes

General guidance for P0456 on most vehicles. Some makers use the same code a little differently; confirm in the service information for your vehicle, put safety first, and see a professional when in doubt.