There is a myriad of things that can make the light come on and identify a problem at a specific location or bank.
Changing the sensor is the first and usually cheapest thing people do. However, things that can be difficult to find like vacuum leaks can also cause the problem.
Also, please tell me how you identified which bank is which. The accessory and valve drives are near the RH fender, which typically would make bank 1 next to the
radiator. But, the water connections are near the LH fender, making the bank next to the radiator bank #2. I honestly don't know.
If you or anyone else has rebuilt this engine, they would know which was which, but guys rebuilding their own engines are hard to find these days.
