2001 corolla chack engine light on.

P0440 = Evaporative Emission System.
P0441 = Evaporative Emission System Incorrect Purge Flow.
P0446 = Evaporative Emission System Vent Control Circuit.
The vehicle is fitted with a system that recycles unburnt fuel in the exhaust gases, usually referred to as the EVAP system. This sounds like a possible issue with the valve built into this system.

code p0440 refers to evaporative emission (EVAP) system--malfunction=== causes --hose connections --intake leak--EVAP canister purge valve
code po441 refers to EVAP --incorrect flow detected==causes the same as for po440
code po446 refers to EVAP system vent control --circuit malfunction===causes --wiring---EVAP can purge valve--ECM
generally I would replace the purge valve as it is common to all codes

This is a CLASSIC symptom of an evaporative emissions issue. GM has had tons of issues with this system. Don't even think about fuel pump at this point. Read this post on how EVAP works.

http://ricksfreeautorepairadvice.com/evaporative-emissions-system-primer/

Then read this post on service bulletins GM has issued on the EVAP system

http://ricksfreeautorepairadvice.com/p0440-p0441-p0442-p0446-evap-codes-on-gm-vehicleshicles-p0440-p0441-p0442-p0446/

yes it would be a smart thing to do and no it is not that hard it should onlt have two bolts holding it on

where is Evap Emission Control System Purge Flow fault

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.

You can actually google this by putting lexus code ### for each one it will tell you what each one means

P0420 indicates you have a catalyst efficiency issue; replacement of the Air-Fuel Sensor should take care of that;
The P0441, P0446 and (I assume P0440); you said 446 twice, indicates a faulty or loose fuel cap; it is not sealing properly.
Please feel free to respond to me if you have any further questions.
A FixYa rating from you regarding my assistance would be greatly appreciated.

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.

When you have P0440, P0441 and P0446, it is a very good bet that the fuel cap was loose, or the fuel cap rubber seal is compromised. You will get all three of those codes every time that the cap is loose. Always make sure that the fuel cap is as tight as you can get it after you refuel.