P0456 on Your 2022 Buick Enclave
A P0456 code on your 2022 Buick Enclave means the ECM has detected a very small leak—approximately 0.020 inches—in the EVAP system. The second-generation Enclave (2018+) uses GM's standard EVAP architecture with a vent valve solenoid and purge valve, powered by a 3.6L V6 engine.
As a GM platform vehicle, the Enclave shares its EVAP system design with other GM crossovers and SUVs. At three-plus years old, your Enclave is entering the early-wear window for EVAP components.
Common Causes
- Gas cap seal wear (33%) — Three years of fueling degrades the seal. Always the first suspect.
- Vent valve solenoid failure (25%) — The #1 component failure on GM vehicles. Controls airflow through the charcoal canister and can stick or develop internal leaks.
- EVAP hose or connection looseness (16%) — Thermal cycling and vibration loosen connections over time.
- Purge valve seepage (13%) — The engine-bay purge solenoid may develop a slight internal leak.
- Charcoal canister issue (8%) — Road debris can damage the underbody canister.
- Fuel tank seal (5%) — Slow gasket degradation.
Diagnostic Steps
- Gas cap test — New OEM cap ($12–$28), clear code, drive for a week.
- Vent valve solenoid check — Locate near the charcoal canister and test for proper operation.
- Smoke test — Professional testing reveals the exact leak location.
- GDS2 diagnostics — GM dealer tool monitors EVAP data in real time.
- Component testing — Individual purge valve and vent valve testing.
Repair Costs
- Gas cap: $12–$28 (DIY)
- Vent valve solenoid: $130–$270
- EVAP hose repair: $80–$200
- Purge valve: $120–$260
- Charcoal canister: $240–$470
Warranty Coverage
Your 2022 Buick Enclave is covered under GM's 3-year/36,000-mile basic warranty through 2025—check your mileage. The federal emissions warranty extends EVAP coverage to 8 years/80,000 miles through 2030. Contact your Buick dealer to verify eligibility.