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- Mar 20, 2021
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Working on a friends 2015 Outback. I have code P0420 showing. (catalyst system efficiency below threshold Bank 1) Research suggested that I do the following:
1. look for exhaust leaks (done, not leaks found)
2. Replace upstream O2 sensor (done) Both sensor are responding. I decided that bank one was on the passenger side of the car. (correct?)
3. Replace Catalytic converter
At this point I am looking for other test that I can perform to confirm that I need to replace that expensive Cat.
I watched the O2 sensor data while it was going down the road and the two sensors are not tracking each other like it would if the cat was missing.
Any advice before I throw a lot of money at this problem?
1. look for exhaust leaks (done, not leaks found)
2. Replace upstream O2 sensor (done) Both sensor are responding. I decided that bank one was on the passenger side of the car. (correct?)
3. Replace Catalytic converter
At this point I am looking for other test that I can perform to confirm that I need to replace that expensive Cat.
I watched the O2 sensor data while it was going down the road and the two sensors are not tracking each other like it would if the cat was missing.
Any advice before I throw a lot of money at this problem?
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