P0456 on the Redesigned 2024 Buick Enclave
A P0456 code on your 2024 Buick Enclave indicates the ECM has detected a very small leak (0.020-inch equivalent) in the EVAP system. The all-new 2024 Enclave features a redesigned interior and updated exterior on GM's C1XX platform with a 2.5L turbocharged four-cylinder engine. As a refreshed model, early EVAP codes are typically minor and fully covered by warranty.
Likely Causes
- Gas cap not fully seated (33%) — The most common trigger. Ensure it clicks firmly.
- Software calibration sensitivity (25%) — Updated models may have ECM calibrations that set EVAP thresholds sensitively. GM addresses these with TSBs.
- Factory EVAP connection variance (18%) — A fitting not 100% engaged from assembly.
- Vent valve solenoid or purge valve (12%) — A slightly out-of-spec component.
- New seal break-in (7%) — Fresh seals needing thermal cycling.
- Transport artifact (5%) — Connection disturbed during delivery.
What to Do
- Check the gas cap — Remove, inspect, reinstall with a click.
- Buick dealer visit — Full warranty coverage, zero cost. GDS2 diagnostics and TSB check.
- Software update — Pending ECM calibrations may resolve the issue.
- Physical repair if needed — Under warranty.
Cost
- Under warranty: $0—covered through 2027 (basic) and 2032 (emissions)
- Gas cap (DIY): $12–$28
Warranty
Your 2024 Enclave carries GM's 3-year/36,000-mile bumper-to-bumper warranty through 2027 and federal emissions coverage for 8 years/80,000 miles through 2032. Let the dealer handle it at no cost.