Possible Causes

WARNING: This page is about a different car, the 2003 Toyota Camry. However, it is still accessible from the selected car via links, so may be relevant.

DTC P0136

Open or short in heated oxygen sensor No. 2 (bank No. 1 sensor No. 2) circuit.

DTC P0137

Open in heated oxygen sensor No. 2 (bank No. 1 sensor No. 2) circuit.

DTC P0138

Short in heated oxygen sensor No. 2 (bank No. 1 sensor No. 2) circuit.
Defective heated oxygen sensor No. 2 (bank No. 1 sensor No. 2).
Defective heated oxygen sensor No. 2 heater (bank No. 1 sensor No. 2)
Defective EFI relay.