Possible causes
– Plugged vapor canister
– Faulty vent solenoid
– Pinched or blocked EVAP hose
– Faulty FTP sensor
– Faulty vent solenoid
– Pinched or blocked EVAP hose
– Faulty FTP sensor
Tech notes
Dirt and dust intrusion into the EVAP canister vent hose assembly, resulting in restricted air flow, may cause this condition.
When is the code detected?
The Powertrain Control Module (PCM) sets the P0446 code if the vacuum decay rate is greater than a predetermined value.
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
– Possible a noticeable fuel odor caused by the release of fuel vapors
– Possible a noticeable fuel odor caused by the release of fuel vapors
P0446 BUICK Description
The Powertrain Control Module (PCM) monitors the performance of the Evaporative Emission (EVAP) system by applying a predetermined level of vacuum to the EVAP system then monitors the vacuum decay rate.