EVAP code P0446. I have replaced perge solinode and the canister perge valve. Can drive car all day long without check engine light coming on,even turning car off for a couple of hours light will not come on. When I let it set over night light comes on after about 1 or 2 minutes. Also after filing up car runs rough for a few seconds(rich, I think). Also when the tank is full the light might not come on after sett ing over night.

code p 0443 refers to evaporative emission (EVAP) canister purge valve--circuit malfunction===causes--wiring--EVAP canister purge valve--ECM
code p 0446 refers to EVAP system vent control--circuit malfunction===causes wiring---EVAP purge valve ---ECM
check the wiring and connection to the purge valve unit

code p0446 refers to evaporative emission (EVAP) system-vent control-circuit malfunction===causes --wiring--EVAP canister purge valve--ECM
code p0455 refers to EVAP system-large leak detected===causes --hose connections--intake leak--EVAP canister---EVap canister purge valve
code p0172 refers to system too rich, bank 1===causes intake blocked---EVAP canister purge valve--fuel pressure ---EGR system---injector/s ---ECM
because the EVAP purge valve appears in all codes I would be inclined to change that unit first the run the fault codes again

P0446 Evaporative Emission Control System Vent Control Circuit Malfunction The code P0446 is set when the engine computer recognizes a fault or restriction at the vent control part of the Evaporative emission control system (EVAP). The description of the fault varies between different car manufacturers, but one thing is common, the code P0446 doesn't directly point to a defective part; some testing might be required to pinpoint the faulty component. What can cause the code P0446: - faulty vent control valve - blockage at the vent hose, vent filter or vent control valve - open or short in the vent control valve circuit - bad charcoal canister - EVAP system leak - faulty EVAP system pressure sensor - bad vacuum switching valve (VSV) - stuck open purge valve (solenoid)

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

code p0441 refers to evaporative emission EVAP system-incorrect flow detected===causes hose connections--intake leak---EVAP canister purge valve
Po144 refers to the same fault and causes
Po446 refers to EVAP system--vent control-circuit malfunction===causes --wiring---EVAP canister purge valve---ECM In all cases codes the canister purge valve gets a mention and then the ECM. I would take it back and ask that the canister purge valve be changed or even ask for a new canister as there are occasions when filling the tank to the filler hole will induce fuel into the canister causing it to malfunction.

Error Code: P0440
Fault Location:
Evaporative Emission (EVAP) System - Malfunction
Possible Cause:
Malfunction Indicator Lamp (MIL) active.
Soution:
Check Evaporative Emission (EVAP) System Sealing.
Check Evaporative Emission (EVAP) Canister Purge Regulator Valve .
Check Evaporative Emission (EVAP) Canister Purge Solenoid Valve .

Error Code: P0441
Fault Location:
Evaporative Emission (EVAP) System - Incorrect Flow Detected
Possible Solutions:
Check Evaporative Emission (EVAP) Canister Purge Regulator Valve .
Perform Output Test.
Check Evaporative Emission (EVAP) Canister Purge Solenoid Valve .
Check Evaporative Emission (EVAP) Canister.
Perform Basic Setting.
Check Pipes between Tank Breathing and Throttle Body.

Error Code: P0446
Fault Location:
Evaporative Emission (EVAP) System, Vent Control - Circuit Malfunction
Possible Cause:
Wiring harness.
Evaporative emission (EVAP) canister purge valve.
Engine control module (ECM).

Continuous Memory Diagnostic Trouble Code (DTC) P0446 or P1450 indicates that Self-Test has detected the Evaporative Emission Control System has excessive fuel tank vacuum. Also, a DTC P0446 indicates a vent control malfunction.

Possible causes:

EVAP canister purge outlet tube (EVAP canister purge valve to EVAP canister) blockages or kinks.

EVAP canister tube (fuel tank to EVAP canister) blockages or kinks.

Fuel vapor elbow on EVAP canister contaminated.

Restricted EVAP canister.

Canister vent (CV) solenoid stuck closed (partially or fully).

Plugged or contaminated CV solenoid filter.

EVAP canister purge valve stuck open.

Fuel filler cap stuck closed (no vacuum relief).

VREF circuit open in fuel tank pressure (FTP) sensor.

Damaged FTP sensor. (fuel tank pressure)

Check for kinks or bends in the fuel vapor hoses/tubes (EVAP canister purge outlet tube and EVAP canister tube).

Visually inspect EVAP canister inlet port, CV solenoid filter and canister vent hose assembly for contamination or debris.

Check CV solenoid filter for blockage or contamination.

The common things I've seen are are mud in the canister and the canister vent solenoid being shot or the wiring to the canister vent solenoid being torn off. The resistance of the solenoid should be 48-65 ohms..
Pick up a Chiltons book and will give you a diagram of where exactly you find the canister. They are like $15 at any auto store. Good luck

I would double check for any air leaks. Replace fuel filter. You will also need to reset computer after new parts are installed. This can be done with a hand-held scanner or diagnostic scanner

P0446 - Vent Control of the Evap System. This Evaporative Emissions System is very complicated. These particular DTCs (Diagnostic Trouble Codes) can be caused by MORE than they tell you. Three MAJOR components in the system can cause this P0446. 1. Charcoal Canister, 2. Charcoal Canister Filter, 3. Canister Close Valve, 4. Fuel Tank Pressure Sensor, 5. Purge Control Solenoid Valve, 6, Wiring and/or connector/connections between them and the ECU. If you wish to trust the computer's diagnostics, then replace the canister close valve (after you have inspected the Evap Charcoal Canister's air filter and find no problems with restrictions of air flow). If the problem comes back, check the Purge Control Solenoid Valve and the operation of the Fuel Tank Pressure sensor - either one of those components, if malfunctioning, can cause a P0446.

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.