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Posted on Jan 02, 2017
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.
Posted on Nov 17, 2008
SOURCE: 2001 corolla P0440, P0441, P0446
P0446 is a "EVAP System - vent control malfunction"
I have a 2000 Corolla and was getting this code, resetting and about 1 1/2 tank or 500 miles later it would come back on. I changed the PCV valve as a first easy fix and no luck. Then I read online about a possible solution was what is called a VSV (Vacuum Switching Valve) and replacing that. I decided to spend the $80 and replace it. It is now 2500 miles later and no more check engine light. The valve is situated under the car just past the gas tank towards the front of the car by the rear axel. It is right by the charcoal canister and is a little tricky to get at but it can be done. Only one tiny screw holds it in it's bracket and I could not get it back in so i zip tied it in there. The unit that I replaced looked to be in pretty good shape but there was some corrosion on it and it looked feasible that it could be defective and apparenlty it was.
Posted on May 29, 2009
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