2000 Chevy Silverado PO442

P0442 OBD-II Trouble Code
Technical DescriptionEvaporative Emission Control System Leak Detected (small leak)

What does that mean?This indicates a fuel vapor leak in the EVAP control system. It means a very small leak has been detected. In fact, the leak can be from a hole as small as 0.04" in diameter. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.

SymptomsYou likely won't notice any drivability problems.

CausesA code P0442 most likely means one or more of the following has happened:

A loose or improperly affixed gas cap
A non-conforming gas cap (i.E. Not factory/original brand)
A small leak/hole in a fuel vapor hose/tube
Other small leak in EVAP system
Faulty vent o-ring seal
Possible SolutionsWith a P0442, the most common repair is to:

Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.
Otherwise, replace the gas cap, or
Inspect the EVAP system for cuts/holes in tubes/hoses