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What might happen if I don't fix it-evap. canister?

I have a '99 Corolla, with approx. 114k miles on it. A few days ago the engine light came on (for the first time ever), so I took off the gas cap and re-tightened it. Still on, had the codes read, P0446, P0441. When I searched for answers online it looked expensive, so I started with the cheapest thing first. I replaced my PCV valve, it was over due to be done anyway. I reset the light also, and drove approx. 20 miles, back on, darn! What are the consequences if I don’t replace the charcoal canister and VSV valves (have you seen where this thing is located-insane!!) I’m not due for inspection for almost another year, please help.


“What are the consequences if I don’t replace the charcoal canister and VSV valves . . . [?]”

I’d say that not passing inspection is the main one. Gas vapors into the environment (eye roll) is another.

However, the one that would upset me is the “Check Engine” light and not knowing if another fault was trying to alert you by triggering the light because it’s already on.

Sometimes the best approach to a problem of this kind is to sweat it out for a few more days. Some of these problems resolve themselves and will turn the light off if that’s the case. Gasoline “flooding” the canister or vent, etcetera, can cause problems and may dry out. Apparently this Make/Model/Year is susceptible to this problem.


Nothing bad will happen to your car. You can postpone repairs as long as you wish, until inspection time rolls around.

I found this somewhere on the web. After cleaning up the guy’s spelling I offer it FWIW:

P0441 EVAP Control System Improper Purge Flow.
P0446 EVAP Control System Vent Control.

Sounds like evap canister needs to be purged. Toyota permits to do so DIY, just very carefully (unless they changed it for your year and on). Any repair manual will have proper instructions. Same time, purge valve is either bad or clogged. I’d also clean EGR valve.

You could try this: replace fuel cap, reset codes at same Autozone. They can do this with scanner. Blow system with a can of Seafoam @ full tank. If the light comes back after Seafoam treatment - purge evap canister and check purge valve.

Lastly, I remember evap canister is a large black canister located between the engine and firewall. Do not confuse it with the a/c expansion canister though. It’s rubber hose vs aluminum ones attached, and evap has clamps for easy removal. Otherwise, about same size and shape.

P0446 doesn’t imply that you need to replace a part. It implies that you need to find an electrical fault with the vent valve. It could turn out that the vent valve itself IS the fault, but it is not necessarily so.

Until that is cleared up I would ignore the P0441 - since the vent valve malfunction can be what is behind that code.

I have no idea why you’d be thinking about the canister at this point. Its the only part of the system that’s really expensive.

To answer your question, NOTHING bad will happen until you need an inspection…

If the CEL has a SERIOUS problem, it will start flashing…

Thank you everyone for responding, I really appreciate the help and advice!!