What does code P0440 mean on a Buick and is it safe to drive?
P0440: Evaporative Emission System Control System Malfunction. Here's what it means on your Buick, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
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What this code means
A general fault in the EVAP system—could be a leak, stuck valve, or sensor issue.
Common causes for your Buick
- Gas cap loose or faulty
- Purge or vent valve stuck
- Charcoal canister or hose leak
Symptoms
- Check Engine Light
Typical fixes
- Replace gas cap
- Test purge/vent valves
- Smoke test EVAP system
Repair cost range
For a Buick, repairs for P0440 often fall between $20 and $400, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on Buick
Buick P0440 EVAP system failure on older platforms starts with the gas cap. On Park Avenue and LeSabre, the EVAP vent solenoid near the fuel tank degrades with age; test it before conducting a smoke test.
Most commonly affected models
Park Avenue 2001–2005Century 2001–2005LeSabre 2001–2005