P0442 means Evaporative Emission Control System Leak Detected (small leak)
What does that mean?
The vehicle's PCM (powertrain control module) tests the evaporative
emissions (EVAP) system for large and small leaks among other
conditions. In the case of this DTC, it 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.
Symptoms
The only thing you will notice is the Malfunction Indicator Lamp (MIL)
a.k.a. Check Engine Light will be illuminated. You likely won't notice
any drivability problems although sometimes a fuel odor may be noticed.
Causes
A 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
Defective vent valve
Defective purge valve
Defective leak detection pump
Possible Solutions
With 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 (we recommend an OEM not aftermarket
part), or
Inspect the EVAP system for cuts/holes in tubes/hoses
More advanced troubleshooting steps include:
Using an advanced scan tool, perform an EVAP leak test
Verify operation of the EVAP purge solenoid / valve
Perform a smoke test to see where the leak is
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