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Dave Nova
Dave Nova, ASE Technician
Category: Kia
Satisfied Customers: 19451
Experience:  ASE Master Certification. 25 yrs experience
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Hello Kia techs. I have a p0446 vent valve circuit malf code

Customer Question

Hello Kia techs. I have a p0446 vent valve circuit malf code on a 2004 sedona. Customer states car starts to run poorly when fuel is about 1/2 tank and less. I pulled down the charcoal cannister and operated vent valve which works fine. There is B+ voltage at the brown wire at the connector to the vent valve and I'm about to check the continuity of the white wire from the the connector to the ecm. Am I heading down the right road or is there something going on I don't understand? Well I don't understand a lot, can you help? I am hoping to get help from someone who has experienced this as I already have access to wiring diagrams etc.
Submitted: 4 years ago.
Category: Kia
Expert:  Dave Nova replied 4 years ago.
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This is not a wiring problem. If there was a problem in the wiring circuit, you would set a P0449 code. The P0446 code sets when the system does not vent properly. Most of the time this is due to the evap vent valve sticking shut intermittently. Before replacing the vent valve, check the tank vent line, charcoal canister, and line over to vent valve to make sure the line is not damaged (collapsed) or restricted in any way.

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Customer: replied 4 years ago.
I have cannister assy out and all the lines look and flow very well. Would this cause the poor running situation she has sometimes? I just hooked up a hose to the big metal pipe that connects to the char cannister (goes into tank) and blew in it and it pressurized tank and then released the pressure back out of the line very slowly. gas cap is off. For such a big line it is either restricted or has an orifice in it. Like I say, gas cap is off and tank seemed to pressurize and then release back slowly out of the line. Fuel filler must have a one way valve. Your thoughts thanks Jack
Expert:  Dave Nova replied 4 years ago.

There may be an orifice in the line. Most of the time when this fault occurs, it is just due to a sticking vent valve. The fuel vapors tend to build up a sticky varnish inside the valve. If the tank is not venting properly, it can make it harder for the pump to draw fuel from the tank and may cause driveabiltiy issues as well.

Customer: replied 4 years ago.
Guess I'll go with the vent valve. I can see that pipe going along the tank and then into another rubber line and that all looks good. Doesn't the gas cap allow air into the tank? How many times have I used you Dave? You're good. Thanks again Jackj
Customer: replied 4 years ago.
It just came to my attention that we put a new vent valve in this 45 days ago. Guess I need to drop that full tank and check that hose restriction. Don't you think?
Expert:  Dave Nova replied 4 years ago.

If the vent solenoid has been recently replaced then you should check restrictions.