P1135 Help

Hi, I recently purchased a 2002 v6 Tacoma. Sweet deal as it only has 180k miles.

Previous owner informed me that there was a check engine light and that they had replaced the o2 sensor that was causing the issue.

The first day of ownership the temperature outside was about 105F. It died once in a parking lot and again the next morning in a parking lot. Both instances the truck was warm and had just started yet only ran for 15-20seconds.

Another day passed and I inevitably got a check engine light. The code it threw was a P1135 bank 1 sensor 1. Upon taking it to dealer to get it serviced and diagnosed. They came back to me by saying the previous owner had places an o2 sensor where an Air fuel ratio sensor is meant to be.
They got a new sensor and replaced that for me and I still have a check engine light with the same code.
Furthermore, the service advisor told me that in doing so my ecu was needing to be replaced.

Wondering if anyone else has experienced this issue or if I should even try to repair/replace the ecu as of now. The truck has had no issues running or lack of fuel economy in the recent days.

Maybe I should reset and clear the code after they replaced the o2 sensor with the correct afr sensor?
Thanks.