Is it safe to drive with a P0456 code?

Severity is low. Address P0456 sooner rather than later — driving with an active check engine light can worsen the problem or void emissions warranties.

How much does it cost to fix P0456?

Repair costs for P0456 typically range from $0 to $300 in the US, depending on the underlying cause. The most common fix is: Slightly loose or failing gas cap seal.

Check Engine Code

P0456

Evaporative Emission Control System Leak Detected (Very Small Leak)

Severity: low DIY difficulty: 2/5 Typical cost: $0–$300

Last updated April 30, 2026

What P0456 means

Pinhole-level leak in the EVAP system. Hardest to find because the leak is so tiny.

Symptoms

Check engine light only

Likely causes (most common first)

Slightly loose or failing gas cap seal
Hairline crack in an EVAP hose or grommet
Failing purge valve

Can I keep driving?

Low — mostly emissions/economy

Typical repair cost

DIY fixes can start near $0 (parts only). Shop repairs for P0456 typically run up to $300 depending on the underlying cause and vehicle. Start with the most common cause — Slightly loose or failing gas cap seal — before throwing parts at it.