need to replace bank 1 and 2. when i look online I only see fron or rear.

Is bank 1 nd 2 both Front???

 

Bank 1 is the first one, bank 2 is the second. Typically the bank 2 sensor is a double check so if it goes out it won't necessarily make it run bad. If the bank 1 sensor goes out it can run really rich and drive like crap.

 

So is bank 1 pre cat & bank 2 post cat???