DTC P0442: Evaporative Emission System Small Leak Detected: Description

EVAP small leak test applies vacuum to EVAP system and monitors vacuum decay. Powertrain Control Module (PCM) monitors fuel tank pressure sensor signal to determine vacuum decay rate. At an appropriate time, EVAP canister purge valve and EVAP vent valve are turned on. This allows the engine to draw vacuum on the EVAP system. After desired vacuum level has been achieved, EVAP purge valve is turned off, sealing system. A leak will be detected by monitoring for a decrease (decay) in vacuum level during a given time period.