P0134 Fault in 2002 PT Cruiser After Catalytic Converter Removal

I replaced my upstream O2 sensor one month ago. A week before that, I removed my catalytic converter due to partial clogging. Now the car is displaying a P0134 code — Inactive Oxygen Sensor. I'm surprised there's no P0420 code given that the catalytic converter has been removed. I recently ordered a new O2 sensor from an alternative online supplier (not the original source). The vehicle runs smoothly, has ample power, and shows no noticeable symptoms other than the check engine light. I've inspected the wiring harness for damage and found nothing suspicious. Fuel efficiency has noticeably decreased. I will update once the replacement O2 sensor arrives and is installed. Any insights or suggestions would be greatly appreciated?