Originally Posted by toyomoho

See link below on changing sensor.

DIY: 1MZ-FE rear bank air fuel/ O2 senor replacement. - Toyota Nation Forum : Toyota Car and Truck Forums

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Using Denso brand sensor as may not have good results with other brands.
Need for any special wrench or socket to fit sensor.

Check Denso or other online parts sites to make sure you get the right sensor.

For emissions purposes, Toyota made a Federal and California car which may have different sensors. This will be specified as for California versus non-California which may as be called Federal.

Appears to be P/N 234-9007.

Sensor is for the V6 engine 3.0 liter (L) also called 1MZ-FE. Sensor location is the rear upstream sensor location.

If the sensor does not come with anti-seize material (a conductive high temp lubricant) on the sensor threads. Apply one sparingly to the threads that is stated to be OK for O2 sensors. Keep any lube OFF the sensor portion the goes into the exhaust pipe as this will contaminate the sensor.

One installed and all is OK. It may take a few trips in the car to turn off the check light
or it can be cleared with a code reader.