O2/Check Engine help

The O2 Sensor 1 is located on the exhaust manifold before the catalytic converter. The O2 Sesnor 2, if so equipped, is located after the CAT. Engines with a V configuration will use Bank 1 and Bank 2 to identify one side of the motor or the other, you only have Bank 1 so this is a tidbit that isn't very useful to you now.

Given the relative young age of your car, I'd be inclined to let well enough alone and wait to see if the code returns. If it does return, I'd look to the connections being dirty as the first cause, and a worn sensor as the second cause.

I've read about a firmware problem with some cars (I don't know if Toyota is included, but I thought I'd throw it out in the General Information category) that read the O2 Sensor input on a too-short timeslice. The sensor has a given amount of time to respond, and if it fails during the time frame given, then it is detected as a failed sensor. Upon tests of the sensors returned under warranty, it was found that the sensors actually worked right, but the time frame was too small to get to the set point reliably. That is, the computer wanted a value in X amount of time, but the sensor required Y amount of time to be acheived on a reliable basis. They rewrote the firmware for the computer to increase the response time frame for the sensor, and this solved the problem. Again, I do not remember if this was a Toyota thing or not, but it makes for a good question for you to ask.

O2 sensor #1 is located on the exhaust manifold.

The code is a proprietary one for Toyotas, and I assume that the code was read at a Toyota dealer, and if it was, the condition and actions that the dealer took are noted for future reference in case it reappears. The part should be covered under the basic 36/36 warranty.

The code probably has 2-trip detection logic, which means that the computer has to detect the problem over 2 trip cycles - cold start, drive X number of miles, catalyst and O2 sensor warmed up sufficiently, etc.