What does code P0455 mean on a Buick and is it safe to drive?
P0455: Evaporative Emission System Leak Detected (Large Leak). Here's what it means on your Buick, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
What this code means
A large leak has been detected in the EVAP system. Could be gas cap left off, disconnected hose, or damaged canister.
Common causes for your Buick
- Gas cap missing or not sealed
- Disconnected or ruptured EVAP hose
- Damaged charcoal canister
- Faulty purge/vent solenoid
Symptoms
- Check Engine Light
- Fuel smell possible
Typical fixes
- Install or replace gas cap
- Inspect and repair EVAP hoses
- Replace canister or valves as needed
Repair cost range
For a Buick, repairs for P0455 often fall between $20 and $500, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on Buick
Buick P0455 follows the GM pattern—gas cap first. On Enclave and LaCrosse, a failed EVAP vent solenoid near the fuel tank is the second most common cause. On Encore with the 1.4T, the purge solenoid mounted on the intake manifold is a known failure point.
Most commonly affected models