check engine light diag code

[hinggu]

After intalling headers, I got the miserable Service engine soon light. Got a reading and here is what it says

HO2S (B1)
[P0139]

HO2S2 (B1)
[P1147]

Detection codition
sensor is constantly 0.3v

check items (Poss. cause)
-Harness or connectors
(The sensor circuit is open or shorted)
-Rear heated oxygen sensor


Here's what was done to install the header. I had to relocate the second O2 sensor behind the second cat which was located behind the car. What can be the cause of this? Is the relocation point to close the the second cat?? Is the extension of the sensor not done correctely, ie mixed up wires or not connected and crimped correctly? Any help would be great!