I have a 2002 Toyota 4Runner and the check engine light costantly returns with the same code (P0446). I have taken this to multiple dealers and local garages to the point of embarassment and anger. They have changed gas caps and ‘Smoke Tested’ the system for leaks, but within a few days, the light always returns. I am looking for any help in resolving this issue. Thanks in advance!
Code P0446 - Evaporative Emission Control System Vent Control Circuit Malfunction.
Why are they fooling around with the gas cap and smoke tests? This code is pretty specific to a problem with a specific circuit. Are you sure the code is not P0442? That code is for a small leak, which the tests are more appropriate for. I have a problem with more than a coupe of shops coming up with the wrong tests. For multiple shops looking at the wrong thing, I’m wondering if you have the right code.
I typed the code from memory, so I could be wrong. I will check it again to be sure as it’s going in for an oil change in about an hour.
At first blush, this DTC (Diagnostic Trouble Code) P0446, “Evaporative Emissions Vent Control system”, doesn’t mean that a leak has been detected. It has to do with the circuits, and components, of those electrical/electronic controls of the vent system.
This isn’t to say that the problem is, or, isn’t complex; but, understanding the system is a great aid to solving the problem. Nope, I don’t have THE answer.
Sometimes, the patient seeks the knowledge, and learns more about his illness than the doctor knows.
Here is one read on the DTC P0446: http://www.toyotanation.com/forum/showthread.php?t=268592
I recalled the code correctly, it is P0446. It is back at the shop that did the original work and they believe they have found the issue. The part will be in tomorrow. I’ll follow up over time just in case someone else has this same problem. Thanks for the replies.