Decoding the P0440 on Your 2024 Buick Enclave
A P0440 code on your 2024 Buick Enclave — completely redesigned for 2024 — means the ECM has detected an EVAP system malfunction. As a first-year model on a new platform with the 2.5-liter turbocharged engine, this is a warranty-covered issue.
The Redesigned Enclave EVAP System
The all-new 2024 Enclave features GM's latest EVAP design with vent valve solenoid, purge solenoid valve, charcoal canister, fuel tank pressure sensor, and fuel filler system.
Most Likely Causes
- Fuel Filler Issue (35%) — Debris or incomplete seal. Cost: $0.
- First-Year Assembly Variation (25%) — New platform connections. Cost: $0 under warranty.
- Vent Valve Solenoid (15%) — GM's common weak point. Cost: $0 under warranty.
- Software Calibration (12%) — First-year ECM tuning. Cost: $0 under warranty.
- Purge Valve (8%) — Factory defect. Cost: $0 under warranty.
- EVAP Line Routing (5%) — New design optimization. Cost: $0 under warranty.
GM Warranty
- Bumper-to-Bumper: 3 years/36,000 miles
- Powertrain: 5 years/60,000 miles
Check the fuel filler. If the code persists, your Buick dealer handles it at no cost.
The Verdict
A warranty repair on the redesigned 2024 Enclave. Check the filler, then let the dealer diagnose using GM's GDS2 platform. First-year models may receive software updates that address EVAP monitoring.