Just put new cats on 2002 5.9L dodge durango and

P0155 - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

if you aren't getting the corresponding bank 1 sensor 1 code, P0135, you may have gotten the wrong O2 sensor, or perhaps it is defective? There is the chance that if you put some anti-seize on the O2 sensor threads or on the exhaust threads that you may have gotten something on the sensor itself clogging it up....

I believe sensor 1 is pre catalytic converter, but this code refers to the internal heater in the O2 sensor... so if all else fails, you may just have to buy or exchange for another and see if it helps your problem