Causes and Fixes P0446 Code: Evaporative Emission Control System Vent Control Circuit Malfunction

How to fix a P0446 engine code: Evaporative Emission Control System Vent Control Circuit Malfunction
A P0446 error code is set when the computer (ECM/PCM) reads an issue with the vent valve, which is a part of the Evap system for emissions.
The P0446 error code is commonly caused by a jammed closed vent valve or mud stuck in the vent.
While Evap systems are similar, they can be designed differently, so it is best to get a diagram for the year, make, and model of the vehicle.
How to Test if Purge Valve Stuck Open Video
• How To Test If Purge V...
How to Test a Purge Valve is Opening and Closing Video
• How To Test Evap Purge...
Most Likely Causes of a P0446 Code:
Bad Vent Valve or Vent Valve Wiring Issue
Bad Charcoal Canister
Less Likely Causes of a P0446 Code: (Will usually get another code)
Bad Gas Cap or Inlet
Evap Leak
Purge Valve
Pressure Sensor
By using this information user assumes all risk of use.
www.backyardmechanic.org

[@HVAC_Mechanic]

Update: I made a full video on all the EVAP components and how to test them; here is a link. kzbin.info/www/bejne/eWbWZIWuaNydepI

[@bbhoustontx]

very good and informative.

[@offgridatliberypoint]

Great video, thank you.

[@macd6351]

Good info!

[@krissymiller5414]

Where exactly is the fuel pressure sensor on a 2005 Chevrolet Cobalt? How can my mechanic friend replace it?

[@jx5189]

I am getting random p0446 I was told that it appears to be a short because the computer won't let him run the vent test, and it is causing it not to vent when it is idling which is causing it not to pass the cars diagnostic check but when I am moving it vents. I just spent a lot of money on other repairs and asked the mechanic if it would cause performance issues or hurt my mileage, he said no. Is p0446 just environmental?

[@jovansolomon9871]

I have a 2013 Ford edge sport with the p0455 and p0446 and I'm 85 percent sure it's the fuel inlet. Ford's early non gas cap vehicles.

[@DenicholasBender-Paige]

Would this make the car not start?

[@mikes.1882]

Does this code clear its self upon parts placement

[@Kiddro22]

After so many cycles(start up) it usually does. Or within the first 100miles driven.

[@dgeezy9]

So is that the reason why when I drive for a couple of minutes my car slows down and stop like it's on break.. and you're right about the gas when I'm filling up my tank is keep on cutting off

[@jasonskriloff3985]

I'm getting a P0441, P0446, P0455 & P4218 on a 2004 Toyota Rav4 and I'm at a loss. I've changed the purge flow sensor, charcoal canister w/ pressure sensor and the majority of the evap hoses. I'm not good with electrical tests so have not done any electrical tests so maybe that's the next step I need to take? The weird thing is that it behaves fine but after a couple of months of driving it will randomly through a cylinder misfire code on any random cylinder and take out the coil pack with it.

[@Earl-vb8sj]

Jason, Toyotas EVAP problems are common. If I were you I'd spend $70 on a smoke machine and some baby oil to help finding a bad vacuum line easier. If you don't mind smoke, a cigar works okay too. If no smoke is present, ensure all vacuum lines are connected correctly. As far as testing electrical, get a 9v battery and some alligator clip test leads. Green/white is ground, red/white is hot. The switches will make a small clicking noise, and save you money. Apologies it took me so long to get to ya. First three codes are for EVAP, but 421 is for your cat. Research can only do so much on trouble codes, each vehicle is unique. Gotta open the hood to solve the problem. Good luck Jason!

[@mr.paulino9318]

I'm getting P0446 on a Toyota Camry. I changed the gas cap and it's still there

[@javiermoreno7746]

I have a 2009 F150 v8 4.6 stx with code number P0446 engine light on, this vehicle has a capless fuel fill inlet system, can this also be a problem? Thanks.

[@HVAC_Mechanic]

Yes, the cap less easy fuel inlet can also leak and cause an issue. Often, they can be cleaned up and made to seal again.

[@javiermoreno7746]

@@HVAC_Mechanic how do l know is not working properly and how can l clean it. Thank you

[@JeshuaNunez7]

@@javiermoreno7746having the same problem on the same truck too thought it was the cap did you find a fix?

[@javiermoreno7746]

@@JeshuaNunez7 on my vehicle 2009 f 150 the problem was the evap valve on the charcoal canister right under the driver's door l didn't have to replace the evap valve the problem was a broken wire to the evap valve, l fixed it and is fine now Hope it helps