P0138 TOYOTA Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2

Possible causes
– Faulty Rear Heated Oxygen Sensor Bank 1
– Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
– Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
– Intake air leaks
– Exhaust gas leaks
– Inappropriate fuel pressure
– Faulty fuel injectors
Tech description
Replacing the Rear Heated Oxygen Sensor Bank 1 usually takes care of the problem.

There is a factory service bulletin for the following Toyota models:
2005