The description of P0136 says bank 1 but I can't figure out which side that is. The steps to test the O2 sensor is via the harness connector in the engine so you could test both LH and RH and see if you can tell which one is bad.
Found another listing of the codes that lists the P0136 as the RH bank.
P0130–P0134 Front HO2S RH Bank
P0135 Front HO2S Heater RH Bank
P0136–P0140 Rear HO2S RH Bank
P0141 Rear HO2S Heater RH Bank
P0150–P0154 Front HO2S LH Bank
P0155 Front HO2S Heater LH Bank
P0156–P0160 Rear HO2S LH Bank
P0161 Rear HO2S Heater LH Bank