2000 Metro P0136

1st post ,be gentle. I own a 2000 Chev Metro 1.3L auto. It's started showing a CEL.My scanner shows a P0136 code "Oxygen Sensor Circuit Malfunction (Bank I Sensor 2) " . When I run the motor and monitor the live data ( I use easyobdII software) the rear O2 sensor shows a constant 1.275V. It never changes. The problem is if I disconnect the connector to it my scanner still shows 1.275V. The forward O2 sensor seems to be ok.It's rapidly fluctuating between 0.2-0.9V. When I disconnect that sensor the scanner shows 0V with a full rich condition.So the front O2 sensor seems fine. Has anyone else had this problem and how was it solved?