I got a 99 v70 with code P0138- 02 circuit high voltage Bank 1 sensor 2.
i replaced the rear sensor, and the same code came on.
the front sensor was replaced at one time, but when i use the scanner to read the voltages, the front sensor doesnt do much switching of voltage.
it appears that the front sensor is bad, but it does not set off a code for the front sensor
i am going to check the wiring from the computer to the sensor for any shorts to ground, then i might just order a new front sensor to try.

has anyone seen any other problems with this code?