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Genchi Genbutsu
Genchi Genbutsu, Toyota Master Technician
Category: Toyota
Satisfied Customers: 4387
Experience:  Toyota Certified Master Diagnostic Technician, ASE Master Technician with L1 Advanced Engine
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Toyota corolla: The engine light is on..P0446..vent..control circuit

Resolved Question:

I have a toyota corolla 2001. The engine light is on and the code is P0446- Evaporative emission system vent control circuit. What can be the problem for this code and how can it be solved/repaired
Submitted: 7 years ago.
Category: Toyota
Expert:  Genchi Genbutsu replied 7 years ago.

How many miles are on the car?



Customer: replied 7 years ago.
Expert:  Genchi Genbutsu replied 7 years ago.

The first step is to check for TSB's (Technical Service Bulletins). These are known issues for this code and car. I just checked on TIS (Toyota Information System) and there are no bulletins.


The next step would be to clear the code by disconnecting the car battery for 1-2 minutes, make sure the gas cap is on tight and drive the car and see if the light comes back on. It may take a few days to a few weeks depending on your driving habits.


If it does come back on, you will need to replace the Charcoal cannister for the Evap system and the CCV(closed cannister Valve) located near the air box. The Toyota parts dept will help locate and price these components for you.


This is a common code for this year and mileage Corolla and will not hurt your car to drive it as is.


Thanks, Genchi


Please ask more of me if you feel the need.




Customer: replied 7 years ago.

After clearing the code the light comes back in couple of days.

If I don't replace the parts you mention above, will this problem affect the results on my emission test, which is due this month. Can I pass the emission test levels?

Expert:  Genchi Genbutsu replied 7 years ago.

It will not effect the emissions at all but I think one of the requirements is that the check engine light be off. If this is the case, then you wont pass. You would have to check with your state as I live in a state with not such testing.


Thanks, Genchi.

Customer: replied 7 years ago.
Can you please help me a bit more? Do I understand correctly that the charcoal cannister and ccvalve are next to air box? And where is the air box located?
Expert:  Genchi Genbutsu replied 7 years ago.

The charcoal cannister is located at the rear of the car, in center of car near muffler. The air box is where your air filter is.


This what the cannister looks like...


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