I had my 1996 C280 OBD Coded. A resulting code was a P0141 which according to my information is a O2 Heater Circuit Malfunction (Bank 1 - Sensor2). I think to correct this error code I have, I need to replace the after catalyst O2 Sensor. Is this correct? Is this an easy item to change out. I saw a O2 sensor tool available, or is it not neccessary?

Thank you for any additional information that can be given.