My 2000 Forester has 96,000 miles on it. A few months ago, the CEL came on. At first it would turn off every couple of days but would eventually pop back on. I first thought it was tied to putting gas in the car, now I think it was just a coincidence.
Over the past two months, I have replaced the catalytic converter with a after market piece (done by a mom and pop muffler shop) and replaced the front o2 sensor three times. The first two times, I used Bosch sensors from an auto parts store and had the code cleared. After about 50 miles the CEL came back on. Just yesterday, I picked my car up from the dealership where they installed a Subaru fron o2. After about 30 miles, the light is back on again. Code is P0133 - heated oxygen sensor, bank 1 sensor 1, circuit slow response.
Now, the dealership is suggesting I need to replace the catalytic converter with a Subaru converter before they can source the issue.
Does anyone have insight into what the issue might me? A less expensive approach to sourcing the problem? Repair ideas? After whats been done, I still don’t feel any closer to getting to the bottom of this!