P0155 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

[Heckler]

2001 4.4

So I have code P0155 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

Previously I had P0171 System too Lean (Bank 1) and
P0174 System too Lean (Bank 2) as well but I found a leak in the intake tube and repaired it then cleared the codes.

A short trip later and the SES light comes back on, I check the codes and now only the P0155 code is there. Could there be another leak somewhere of is it likely that the 02 sensor is bad? Anyone know of DYI's for replacement?

Also, which side is bank 2?

Thanks