P0456 on Your 2024 Buick Envision
A P0456 code on your 2024 Buick Envision indicates the ECM has detected a very small leak (0.020-inch equivalent) in the EVAP system. Your Envision uses GM's EVAP architecture with electronic vent and purge valve controls, paired with its 2.0L turbocharged four-cylinder engine. On a new model, P0456 is typically minor and fully covered by warranty.
Likely Causes
- Gas cap not fully seated (35%) — The most common trigger across all vehicles. Ensure the cap clicks firmly after every fill-up.
- Software calibration sensitivity (23%) — GM may have ECM calibration updates that adjust EVAP monitor thresholds for the 2024 model year.
- Factory EVAP connection variance (18%) — A quick-connect fitting not fully engaged from assembly can create an intermittent micro-leak.
- Vent valve solenoid or purge valve (12%) — A component slightly out of spec, though uncommon on new vehicles.
- New seal break-in (7%) — Fresh rubber seals and gaskets may need thermal cycling to fully seat.
- Transport artifact (5%) — A connection disturbed during delivery or pre-delivery inspection.
What to Do
- Check the gas cap — Remove, inspect, and reinstall with a firm click. Clear the code if you have a reader.
- Buick dealer visit — Full warranty coverage means zero cost for diagnosis and repair. The dealer uses GDS2 diagnostics and checks for applicable TSBs.
- Software update — The dealer applies any pending ECM calibrations.
- Physical repair if needed — Smoke test and component replacement, all under warranty.
Cost
- Under warranty: $0—covered under GM's 3-year/36,000-mile warranty through 2027
- Gas cap (DIY first try): $12–$25
- Federal emissions warranty: 8 years/80,000 miles through 2032
Warranty
Your 2024 Envision carries GM's 3-year/36,000-mile bumper-to-bumper warranty through 2027, the 5-year/60,000-mile powertrain warranty through 2029, and federal emissions coverage for 8 years/80,000 miles through 2032. Let the dealer handle it at no cost.