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I have a 2001 Toyota Tundra and recently I did a check engine light diagnosic and got the code p0446 Evaporative Emission Control System Vent Control Circuit Malfunction. I was wondering if this could be the Charcoal canister or the vent, and is it possible to repair/clean them myself. ALSO what i should be looking for when trying to make the check engine light go off. THanks
 

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P0446 usually means the vent control valve is stuck or is not responding to the ECM's request to function. It could be stuck open due to debris, but that will usually have a gross leak or small leak DTC stored along with the P0446. If you can, take the vent control valve off of the canister, check the tubes for clogging and clean 'em out. While you have the valve off, maybe apply a 12v source and ground, see if the plunger operates. Worst case scenario, it's a harness or ECM issue. Best case scenario, there's a spiderweb in the vent tube :)

Hope this helps and good luck!
 

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^^^ or the ECM THINKS that the vent valve is sticking or broken because it only knows its working properly due to change in pressure in the system which is monitored by the Vapor Pressure Sensor

EVAP diagnostics without a scan tool, vacuum pump, and a smoke machine is not only difficult enough when you have those things, but can be very time consuming. i was just on my ALLDATA account and it says that the P0446 code will come from the Vapor Pressure Sensor not reading correct pressures or vacuum when evap is operating or not. without being able to monitor that pressure sensor, youll be pretty much throwing parts at your truck for no reason.. i hate to say bring it to a auto technician becuase it will most likely cost you more money, but it may end up saving you some in the long run.

places of possible fault--- Pressure sensor, vent valve, ECM, system wiring, broken or cracked canister.
 

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This is true, but, I would check the vent hose for obstruction and canister for leaks (like cavi said) before I went and dropped $100 on a diag. fee.
 
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