What does code P0440 mean on a GMC and is it safe to drive?
P0440: Evaporative Emission System Control System Malfunction. Here's what it means on your GMC, 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 GMC
- 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 GMC, 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 GMC
GMC P0440 on Sierra and Yukon trucks typically traces to a cracked EVAP purge solenoid hose near the intake manifold or a gas cap seal. These trucks share the same EVAP architecture as Chevrolet Silverado and Tahoe—purge solenoid hose inspection is the first step.
Most commonly affected models
Sierra 1999–2007Yukon 2000–2006Terrain 2010–2017