EVAP

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📖 YOUCANIC Automotive Glossary

The EVAP (Evaporative Emission Control) system captures gasoline vapors from the fuel tank to prevent atmospheric release. Components include the charcoal canister (stores vapors), purge valve (releases vapors to intake for combustion), vent valve (controls airflow for purging and leak testing), fuel tank pressure sensor, and fuel filler cap. The ECU periodically tests the system for leaks by sealing it and monitoring pressure.

EVAP codes are among the most common CEL causes: P0440 (System Malfunction), P0442 (Small Leak), P0455 (Large Leak — often a loose gas cap), P0446 (Vent Circuit). Check the gas cap first. The YOUCANIC UCAN-II performs EVAP tests including commanding purge/vent valves while monitoring tank pressure.

Synonyms:
Evaporative Emission Control, Vapor Recovery, EVAP System
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