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Toyota Repair/CODE PO446

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Question
QUESTION: 2000 RAV 4 L 170K MILES WELL SERVICED....WHAT ARE THE POTENTIAL FIXES FOR THIS CODE ?? EVAP EMMISSION SYS VENT CONTROL CIRCUIT??
THANKS IN ADVANCE ......LARRY

ANSWER: hello, clear the diagnostic code and replace the gas cap with a factory OEM cap, see if the code comes back ,then let me know.

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QUESTION: The unit has the original OEM gas cap.....it smokes white/grey on start-up and has not had to go through emissions for several years due to geography. It runs and accelerates fine, the only downside is the code.Could it be an emissions valve...egr or something else in the vent control circuit??? Pls respond...thanks Larry

ANSWER: Thanks for the reply
The white/gray smoke is usually due to leaking valve seals and do not cause this code, it is also not EGR related, the code is for a gross leak in the evap control system, the first thing is to check under the hood for any emission hoses that may be disconnected between the air filter and the charcoal canister and switching valves, I'll give you the most likely things that can give you this code other than hoses:
A leaking charcoal canister, a faulty purge valve (this is the one that has the green cap on the hose)a canister closed valve, this attached to the air filter. Without testing the system for leaks by either using Toyota's test equipment or a smoke induction machine it's very hard to say which is the actual problem.

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QUESTION: WILL TRY TO REPAIR....IS THE REPLACEMENT OF VALVE SEALS WORTH IT? how DIFFICULT IS IT ON A 4CYL? a DO IT YOURSELF PROJECT OR BIG $$...FROM A SHOP??

Answer
Valve seal replacement reqiures some special tools an the camshafts have to be removed from the cylinder head, not really at DIY operation. The usual charge is about eight hours labor plus the cost of the seals and gaskets, the whole job runs well over $1000 at the dealer but if you can locate s repair shop that is willing to do this without removing the cylinder head you can save few hundred dollars.

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