Review on DENSO 234 9022 Fuel Ratio Sensor by Robert Mulrooney

Great, works as described. This fixed the P0138 code in my 2012 Toyota RAV4. Yes, if you google the code, code P0138 indicates that it is a faulty oxygen sensor - BANK 1 SENSOR 2 (downstream). However, this is not the case and after diagnosing it by checking the resistance you will see that the supposedly faulty sensor is working normally. After searching the internet for clues, I found that while the code the car was giving out indicated a faulty low flow sensor, it is actually a high flow sensor, BANK 1 SENSOR 1, which it is also is. Changed and voila - Check Engine and Traction Lights are gone. The moral of the story is: google and search car/model forums for real answers and solutions, and don't rely on Toyota's expensive and complicated software to give you reliable solutions.