These codes are all for the Evaporative Emissions System.
P0440- Evaporative emissions system fault- just saying there's something wrong with the system.
P0441- Evaporative emissions system- Incorrect purge flow- saying that the system isn't purging the raw fuel vapors (hydrocarbons- HC) as well as it should.
P0446- Evaporative emissions system- Control valve circuit low- there is a valve, usually located on the charcoal canister at the rear of the vehicle, that opens to allow fresh air to enter the evaporative emissions system as the engine vacuum purges the fuel vapors from the charcoal canister and closes when purge is not needed to prevent leakage of those fuel vapors to the atmosphere (HC is a greenhouse gas and is regulated as such by the fed gov't).
Given that you have the incorrect purge flow code and the control valve code together, my bet is that the
vent control valve has failed (causing the P0446) and is not opening to allow fresh air into the system to displace the air from within the system that is being pulled to the engine. Since you have no fresh air entering the system, the engine will pull a vacuum on the system instead of the vapors "flowing" into the engine (causing the P0441).
I hope that this is helpful to you!!!
ASE Master Technician with L1 and X1
Certifications; Nissan Scope Technician; Chrysler Level 3 Silver Technician- 12+ years experience.
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