I HAVE A CODE PO446 , I REPLACED THE GAS CAP ,PURGE VALVE SOLENOID, A VAC LINE TO THE SOLENOID AND CODE KEEPS COMING UP

Get a new Gas Cap. The evap is setting due to much vacuum around cap.

Possible causes
- Missing or loose fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- EVAP canister or fuel tank leaks
- EVAP system hose leaking
- Fuel tank leaking
What does this mean? Tech notes
The P0455 it's a very common code, because the code is set if the gas cap is loose or missing. Start by tighten the gas cap and clearing the code. In most cases the code can be clear by disconnecting the car battery for about 30 minutes.
What does this mean? When is the code detected?
Evaporative Emission System (EVAP) control system has a very large leak such as fuel filler cap fell off, EVAP control system does not operate properly.
Possible symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Possible a noticeable fuel odor caused by the release of fuel vapors
P0455 Mitsubishi Description
This diagnosis detects leaks in the Evaporative Emission System (EVAP) purge line using engine intake manifold vacuum. If pressure does not increase, the Engine Control Module (ECM) will check for leaks in the line between the fuel tank and EVAP canister purge volume control solenoid valve under the following vacuum test condition.
The vacuum cut valve bypass valve is opened to clear the line between the fuel tank and the EVAP canister purge volume control solenoid valve. The EVAP canister vent control valve will then be closed to shut the EVAP purge line off. The EVAP canister purge volume control solenoid valve is opened to depressurize the EVAP purge line using intake manifold vacuum. After this depressurization is implemented, the EVAP canister purge volume control solenoid valve will be closed.

Read more: http://engine-codes.com/p0455_mitsubishi.html#ixzz3NlVyARyX

Possible causes - Missing or loose fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- EVAP canister or fuel tank leaks
- EVAP system hose leaking
- Fuel tank leaking The P0455 it's a very common code, because the code is set if the gas cap is loose or missing. Start by tighten the gas cap and clearing the code. In most cases the code can be clear by disconnecting the car battery for about 30 minutes.

When is the code detected? EVAP control system has a very large leak such as fuel filler cap fell off, EVAP control system does not operate properly. Possible symptoms - Engine Light ON (or Service Engine Soon Warning Light)
- Possible a noticeable fuel odor caused by the release of fuel vapors P0455 Buick Description This diagnosis detects leaks in the Evaporative Emission System (EVAP) purge line using engine intake manifold vacuum. If pressure does not increase, the Engine Control Module (ECM) will check for leaks in the line between the fuel tank and EVAP canister purge volume control solenoid valve under the following vacuum test condition. The vacuum cut valve bypass valve is opened to clear the line between the fuel tank and the EVAP canister purge volume control solenoid valve. The EVAP canister vent control valve will then be closed to shut the EVAP purge line off. The EVAP canister purge volume control solenoid valve is opened to depressurize the EVAP purge line using intake manifold vacuum. After this depressurization is implemented, the EVAP canister purge volume control solenoid valve will be closed.
if tightening the cap or replacing the cap does not help take your car to a shop to have it diagnosed as it requires special tools/equipment to test this and get an accurate results to find what needs replacing.

this is the vent solenoid and canister



this is the purge solenoid both solenoids work together

hope it helps

hopefully the humming is coming from the fuel tank area that would be the fuel pump running-denny

Trouble Code: P0446

EVAP Vent Control Solenoid Circuit Malfunction

Possible Causes:


Vent solenoid circuit open, shorted to ground or to power (B+).Vent control solenoid is damaged or has failed..PCM has failed.TSB 00-060 (7/00) contains information related to this code.Trouble Code: P0455

EVAP System Gross Leak (0.080") Detected

Possible Causes:


.EVAP control system pressure sensor is damaged or has failed.EVAP purge solenoid or canister vacuum line loose or off.EVAP purge solenoid is damaged or has failed.EVAP emission canister is dirty, restricted or full of water.EVAP canister vent control valve is damaged or has failed.Fuel tank cap loose, missing or it is the wrong part number.Fuel tank temperature sensor is damaged or has failed.Fuel tank vacuum relief valve is damaged or has failed.Large leak in the EVAP canister or in the fuel tank area.ORVR system is damaged or has a large leak in a component.Refueling control valve is damaged or has failed.Vacuum hose leaking between intake manifold and Purge valve.Here are the codes,take part back and get refund.

The code is for a large leak in the EVAP system such as a loose or missing gas cap. But it could also mean a loose or missing hose to the canister or other leak in the tank.
The computer vents the tank several times an hour while the engine is running, and it checks the system by pressurizing the gas tank. If the tank will not hold pressure the code is set.
You may have to check the top of the tank where the fuel pump gasket is, as well as the vent lines to the front of the car.
A mechanic would perform a smoke test to look for leaks.

You must have a leak somewhere in the tank, because gas caps seal and vent at a certain pressure (1-2psi) a smoke test would check it. Try clearing the code first. If it keeps comming up, test it.

most of these codes appear if the driver forgets to put the gas cap back on, or the gas cap seal is bad. double check the vacuum line from the throttle body to the purge solenoid for leaks. The best way is with a smoke machine. There could also be an issue with the purge solenoid or the electrical connection to it.

P0446 Evaporative Emission System Vent Control Circuit.
The following are descriptions of all Evaporative possible codes:

P0441 Evaporative Emission System Incorrect Purge Flow
P0442 Evaporative Emission System Leak Detected (small leak)
P0443 Evaporative Emission System Purge Control Valve Circuit
P0444 Evaporative Emission System Purge Control Valve Circuit Open
P0445 Evaporative Emission System Purge Control Valve Circuit Shorted
P0446 Evaporative Emission System Vent Control Circuit
P0447 Evaporative Emission System Vent Control Circuit Open
P0448 Evaporative Emission System Vent Control Circuit Shorted
P0449 Evaporative Emission System Vent Valve/Solenoid Circuit
P0450 Evaporative Emission System Pressure Sensor/Switch
P0451 Evaporative Emission System Pressure Sensor/Switch Range/Performance
P0452 Evaporative Emission System Pressure Sensor/Switch Low
P0453 Evaporative Emission System Pressure Sensor/Switch High
P0454 Evaporative Emission System Pressure Sensor/Switch Intermittent
P0455 Evaporative Emission System Leak Detected (large leak)
P0456 Evaporative Emission System Leak Detected (very small leak)
P0457 Evaporative Emission System Leak Detected (fuel cap loose/off)
P0458 Evaporative Emission System Purge Control Valve Circuit Low
P0459 Evaporative Emission System Purge Control Valve Circuit High
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At least the cap isn't loose for the gas tank.

I would clear the code with an OBD-II Scanner 'erase code' button, and see how long it takes for it to come back.