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Ask Skyvisions Your Own Question
Skyvisions, ASE Certified Technician
Category: Toyota
Satisfied Customers: 14412
Experience:  Toyota Master Diagnostic
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Customer Question

JA: Just to clarify, what's the exact code? And have you tried to reset it?
Customer: I did reset it twice
JA: Are you fixing your 4Runner yourself? What have you tried so far?
Customer: new gas cap
JA: Anything else you want the mechanic to know before I connect you?
Customer: is there a charge?
JA: You just pay a $5 deposit now and the rest only when you get a reply from the Toyota Mechanic. All of this is 100% satisfaction guaranteed, so you can get a refund if you're not happy for any reason.
Customer: thanks anyway, trouble shooting on my own for now.
Submitted: 7 months ago.
Category: Toyota
Expert:  Skyvisions replied 7 months ago.

HAs there ever been any other code set with the P0446 code? Do you have the definition of the code or do you need that too?

Customer: replied 7 months ago.
No just the code po446 and yes I know what P0446 code definition. P0446 is an OBD2 diagnostic trouble code that indicates a fault within the evaporative emission control system. Other EVAP system codes may be seen with P0446.
Customer: replied 7 months ago.
No email is fine. I just bought this a month ago and no codes were evident and still wouldn't have stopped me from buying it. Its runs perfect and looks perfect until after owning this for a few weeks and then po446 came on.
Expert:  Skyvisions replied 7 months ago.

More specifically this code P0446 indicates there's a problem with the vent valve or CCV which stands for close canister valve. This is a control valve that is mounted on the left inner fender well near the brake master cylinder there is also a purge valve located there too. The reason why the 446 code sets is because it sees a leak detection when it runs a vapor pressure test and it controls that valve to close. Either the hoses are off or missing or the valve itself is not opening and closing. You can test the solenoid with battery voltage and ground to make sure clicks if you don't have an active testing scan tool otherwise it is difficult to accurately diagnose evaporative emission systems without a smoke machine and a pressure tester for the EVAP system.

Customer: replied 7 months ago.
Do you think its the cannister or no it sounds like. You think its a vacuum leak?
Customer: replied 7 months ago.
I guess it would be prudent to take to the dealer for them to test the CCV
Expert:  Skyvisions replied 7 months ago.

If you live where heat is an issue it's possible could be a problem in the canister if all the hoses are intact and no cracks or leaks which normally would cause a P0 440 code to set along with the 446 code it is likely the close canister valve or CCV. It will allow air to pass through it only once opened or closed. You can apply voltage and make sure the seal inside the valve is working and in fact the valve itself is clicking. It's cheaper to just replace that versus paying someone to diagnose it. The canister is a lot more expensive. Unless you can find a dealer to do a correct evaporative emissions test to give you 100% diagnosis but is very difficult to find quality diagnosticians in the shop.

Customer: replied 7 months ago.
I live in Maryland and it gets hot in the summer but the temperature has come down significantly since August, so I would say I live in a hot state 2-3 months a year. So you think going at it from the valve stand point is better place to start?
Customer: replied 7 months ago.
Ok I'll give that a shot and see what happens. thx.
Expert:  Skyvisions replied 7 months ago.

Sorry had to step away from my computer for a bit that is correct just replacing the bow may be cheaper than paying some diagnose this and could solve the problem. If you have not done so please do not forget to rate the information that I provided you at three or higher.