What does code P0442 mean on a GMC and is it safe to drive?
P0442: Evaporative Emission System Leak Detected (Small Leak). 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
The EVAP system has detected a small leak. Often caused by a loose or faulty gas cap or a small hose leak.
Common causes for your GMC
- Loose, damaged, or wrong gas cap
- Cracked or disconnected EVAP hose
- Faulty purge or vent valve
- Leaking charcoal canister
Symptoms
- Check Engine Light
- Often no driveability issues
Typical fixes
- Tighten or replace gas cap
- Smoke test EVAP system
- Replace damaged hoses or valves
Repair cost range
For a GMC, repairs for P0442 often fall between $15 and $300, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.
Known issues on GMC
GMC P0442 mirrors Chevrolet's pattern on shared platforms. On Sierra and Yukon, the vent solenoid near the fuel tank is a common small-leak source. Check the filler neck on older models in salt-belt regions.
Most commonly affected models
Sierra 2004–2014Yukon 2004–2014Terrain 2010–2015