first of all, thanks to salim and lex for your helpful advice.
Yes, I am starting to think that I should take my vehicle to toyota for them to have a look at.

But meanwhile, would it be okay to drive around with CEL p0440, p0446?
the mechanic did reset the code for now, so it is turned off.

I am not sure if these codes are something serious that we should take our vehicle to toyota asap, or would it be okay for us to drive until the light comes back on or until we finally make decision of where to take our vehicle to. (We drive about 15-20 miles/ day)

Would these codes cause my car to stop all of sudden in the middle of highway??? or create a danger situation??

Thanks,

Shawn

 

There can be some minor issue with acceleration, but that I noticed when I was back in Mexico City and on other vehicles. It would be okay to continue to drive around. There is a reason I still tend to tell people to eventually get it fixed and that is because I have seen (though not on an RX300), the charcoal canister rupture after time. I probably wouldn't panic over this as in those cases it was due to the person overfilling their gas tank.

However, driving will 99.9% not cause an issue in this case.

 

SHY820424 - I got the same 2 error codes. How did you get it resolved? thx.

 

Sorry to bring up an old thread but, I thought I'd share my experience with codes: p0440, p0446.
After resetting the codes via disconnecting the battery the cel, vsc off , and trac off lights would return after @ 50 miles of driving. Well, after 3 times of resetting the system I threw in the towel and scheduled an appt. with the dealership and crossed my fingers. I figured it wasn't going to be expensive seeing how my rx ran fine and had typical mpg's.
Well it turned out to be an evap hose that was disconnected. Fix was done in 30 min. and was charged 1/2 hour labor. The cel's were erased and all is well after 65 miles of driving.

Interestingly, the service tech asked if someone had worked on my vehicle recently? I said no, Buuuut now that I think of it I did have the oil changed about 2 months ago at a Firestone and they did do a "courtesy check" on it. Now I can't prove that they accidently disconnected the hose, but I sure as hell will change my oil next time. Even if I'm in a hurry, I better off doing it myself and finding time to do it.

 

Based on my personal experience, Firestone has a policy to check air filters without asking the owner in advance. They do this hoping to sell you an air filter. I'm surprised they didn't tell you how dirty your filter is and tell you are ruining your gas mileage and damaging your engine!

 

Acerx300- Now you know why I have changed my own oil my entire life (only 1 time in my life that I can remember that I didn't pull the pan plug and that was after major warrantee work) I spent my life in one form or another of automotive work and decided early on that I didn't want the average mechanic anywhere near my vehicle. I could write a book (a very large one) on the screw-ups I've seen over the years and the customer seldom ever knows (and will likely pay down the road for something the technician actually screwed up).