I have a 2001 Nissan Sentra that keeps showing a P0140 DTC. I was intitially getting a code for the heater circuit so I replaced the sensor. Thats when I started getting P0140 instead. I checked wiring for shorts and continuity to the ECM as stated in the factory service manual. Everything checked out good so I replaced the sensor again and have the same results. The code states bank 1 however the factory service manual states bank 2. in the end I ended up replacing all 4 sensors since one by one I was getting codes. All DCT's cleared up after replacing except this P0140 which keeps coming up. On the scan tool the sensor reads a constant 1.275 volts. I have checked with 2 different scan tools with the same results. I also checked all grounds and cleaned and tightened them as well. I don't know what else to try.