Possible Causes
Missing or loose fuel cap
Incorrect fuel filler cap used
Fuel filler cap remains open or fails to close
Foreign matter caught in fuel filler cap
EVAP canister or fuel tank leaks
EVAP system hose leaking
Fuel tank leaking
Faulty vent solenoid
Faulty EVAP purge switch
الأسباب المحتملة
Possible Symptoms
Engine Light ON (or Service Engine Soon Warning Light)
Possible a noticeable fuel odor caused by the release of fuel vapors
الأعراض المحتملة
Description
Code P0440 GMC Description
The Powertrain Control Module (PCM) tests the Evaporative Emission (EVAP) system for the following conditions:
– Large and small leaks
– Excess vacuum
– Purge flow during non-commanded conditions
– Fuel Level and Fuel Pressure sensor faults
– EVAP Purge and Vent Valve faults
The PCM monitors the Fuel Tank Pressure sensor in order to determine the level of vacuum/pressure in the EVAP system. The PCM commands both the EVAP Purge Solenoid and the EVAP Vent Valve ON when the conditions are met in order to apply an engine vacuum to the EVAP system. The PCM commands the EVAP Purge Solenoid OFF once the system has reached a predetermined level of vacuum. This test verifies if a vacuum can be achieved in the EVAP system. Failure to develop a vacuum may be caused by a large leak or a restriction.
P0440 GMC Code – Evaporative Emission System
