99 4runner TSB Oxygen Sensor Improvement

I found out that there is a TSB for the Oxygen sensor. Does anyone know what the full story is on this. I have had check engine come on and the dealer told me I needed new Catylitic converters. I have heard that the o2 sensor can be causing this.

Yes, there is an HO2 sensor after the cat converter that monitors the cat converter fuction. If there is a Check Engine Light and code saying bad cat converter, then it is the HO2 sensor causing this trouble code. I would check the HO2 sensor function before you replace the cat converter.