P0442 Evaporative Emission Control System Leak Detected (Small Leak)
The EVAP system detected a small leak (approximately 0.040" diameter) during a self-test.
Definition
P0442 is the most common EVAP code and the most common cause is a loose, missing, or failed gas cap. The next most likely culprit is a cracked or disconnected EVAP hose. Less commonly, the leak is at the purge or vent solenoid.
Common causes
- Loose, missing, or worn gas cap
- Cracked or disconnected EVAP hose
- Failed purge valve solenoid
- Failed vent valve solenoid
- Damaged charcoal canister
- Leaking fuel filler neck
Common misdiagnoses
- Replacing the gas cap multiple times when a hose is the real leak. Use a smoke machine to find the leak.
Troubleshooting steps
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1. Tighten and inspect the gas cap
A worn or improperly seated cap is the #1 cause. Replace if the seal is hardened or cracked.
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2. Smoke-test the EVAP system
With a low-pressure smoke machine, pressurize the EVAP system and look for escaping smoke at hoses, the canister, and the filler neck.
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3. Test purge and vent solenoids
Command each closed via scan tool and verify they hold pressure.