Replace Oxygen Sensor and with original catalytic convertor?
I brought my '15 Subaru Legacy (2.5i) to the mechanic to have him check why it would occasionally and momentarily ride rough. He discovered that I had a bad O2 sensor which is messing w/ my catalytic convertor that also caused a spark plug to fail which is resulting in 1 of the cylinders misfiring.
He tells me I need to replace the Oxygen Sensor, Spark Plug, and Catalytic convertor.
I'm curious to know if it's an acceptable idea to replace the O2 sensor and spark plug, but leave the original catalytic convertor? After a bit of conversation and teeth pulling, my understanding is that it's not blocked and that the O2 sensor is the root of the other problems.
Vehicle has 80k miles.
