An oxygen sensor slow response or low activity trouble code is almost always a faulty oxygen sensor. There are a few other things to consider before replacing the oxygen sensor.

In most cases, a slow response DTC gets fixed with oxygen sensor replacement.

Here’s part II of my wideband O2 case study. I cover some further voltage and current testing on this vehicle and go deeper into the operation of this type of wideband sensor.

In this first part of a two-part series, I get my hands dirty on a 2000 Lexus RX-300 with a wideband O2 sensor problem.