General Information

P0442 Evaporative Emission System Leak Detected (small leak)

General Information

Component Location





General Description

Due to the increasing ambient temperature of the fuel, fuel vapors are generated in the tank. In order to control the release of these vapors to the atmosphere, the evaporative emissions control system is used. The evaporative emission control system reduces hydrocarbon (HC) emissions by trapping fuel tank vapors until they can be burned in the combustion process. Evaporating fuel is stored in a charcoal canister until it can be flushed into the intake manifold. The evaporative emission control system is made up of a fuel tank that can be completely sealed from outside air, a Fuel Tank Pressure Sensor (FTPS), a Canister Close Valve (CCV) that seals the canister from the outside air, a canister filled with activated charcoal granules, a Purge Control Solenoid Valve (PCSV). The evaporative emission system can be checked for leaks by sealing the system off from the outside air, creating a vacuum, and monitoring if the system can hold that vacuum sufficiently for a set amount of time. If it cannot, a leak exists somewhere in the system.

DTC Description

This test detects a leak by measuring an increase of vacuum in the fuel evaporative system. A leak in evaporative system can allow hydrocarbons to leak from the tank to the atmosphere when the engine is off. The test should be calibrated to detect 0.02"~0.04" (0.5 - 1mm) leakage.
If there is a small leak above the threshold value in the fuel evaporative system, PCM sets P0442.

DTC Detecting Condition