2001 Toyota Corolla Check Engine Codes P0441B And P0446B - Toyota Corolla, Chevy Prizm (1998-2008)

Guest psychoanalyst

Hello,

I am new to this forum, and even without being a member in the past, I have got a lot of help from the amount of information here.

This time around, I have encountered codes that I need more help with. I got the codes from Midas Auto in Atlanta.

I am aware of the problems associated with the codes themselves (though I am not sure what the B is for).

P0446 : Evaporative Emission control system Vent control circuit

P0441 : Evaporative emission control system incorrect purge flow

I noticed the problem for the first time yesterday morning, and coincidentally (?), I had filled my gas tank to its full capacity for the first time ever (yes, that is right!) the night before.

I have come across posts that mention that overfilling the gas tanks and/or loose gas tank caps can cause the above codes, so I wonder if that might be the case?

If so, do you think it would be advisable to wait for a couple of more days to see if lower fuel levels can fix the problem? Would the check engine light go off automatically?

Otherwise, I have had no problems whatsoever driving my car.

I would appreciate any help. Being a student, I would definitely not mind saving the $400 odd I would apparently have to spend if it was a problem with the charcoal canister/solenoid valve.

Regards.

Check light for EVAP codes will go off automatically. Doesn't mean the problem has gone away, as the trouble code will be stored in memory.

As for most EVAP issues, you won't see any drivability issues - this will only affect emissions. So if you need the car inspected or live in an area with emissions testing, the car will automatically fail with a CEL.

Since the circuit malfunction code popped up (PO446), this could indicate that you have some other underlying cause for the problem. Could be anything from a simple vacuum leak, to a cracked vent tube, bad gas cap gasket, damaged tank cutoff valve, faulty vent valve, bad purge valve, cracked vapor canister, etc. The list goes on.

The P0441 is more focused, could be a bad VSV valve - but you should get the car EVAP tested to be sure. A good shop should run an exhaustive check of the system - many will fill the EVAP system with a tracer smoke, and use a sniffer wand to pinpoint the leak as they actuate the various valves.

As for the codes realted to the fully filled tank - unless you knowingly overfilled the tank (topping off, kept pumping past the automatic shutoff on the pump) - this is likely just a coincidence.