Sorry it's been such a difficult time for you. I'm not sure why "mechanics" can't look up some service info. We have a lot of great technicians on here, so if there's a question, I can answer one of the other guys will definitely be able to. The Catalyst monitor can't pass if the PCM sees the rear Oxygen sensor voltage mirroring the front Oxygen sensor on that Bank of the engine. That tells the PCM that the converter on that side is not burning off the left-over hydrocarbons and CO. The hydrocarbons are raw fuel, and the CO (carbon monoxide) is partially burned fuel, both are a byproduct of combustion engines. So, when the converter is doing its job, the rear oxygen sensor should have a steady voltage reading.
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Monday, July 10th, 2023 AT 3:48 PM