What does code P0456 mean on a BMW and is it safe to drive?
P0456: Evaporative Emission System Leak Detected (Very Small Leak). Here's what it means on your BMW, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
What this code means
The EVAP system has detected a very small leak—often smaller than P0442. Commonly caused by a loose fuel cap or hairline crack in a hose.
Common causes for your BMW
- Loose or worn gas cap seal
- Hairline crack in EVAP hoses
- Minor leak at purge or vent valve fittings
Symptoms
- Check Engine Light only
- Usually no noticeable driving symptoms
Typical fixes
- Inspect and replace gas cap if seal is hardened or cracked
- Smoke-test EVAP system to locate tiny leaks
- Repair or replace leaking hoses and fittings
Repair cost range
For a BMW, repairs for P0456 often fall between $25 and $350, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on BMW
BMW P0456-equivalent small leak codes often come from a leaking DMTL pump check valve or a micro-crack in the EVAP hose. BMW's DMTL test runs at night in cold conditions—the fault may not reproduce during shop testing. Use ISTA to run the DMTL diagnostic test sequence before replacing parts.
Most commonly affected models