diagnostic trouble code po146 pops up on scanner however there is no sensor ther

Hello, There are two on each side, for a total of 4. Position 1, 2, 3, and 4. Position 3 is a post-cat sensor. If you don't know which one, just unplug one, at a time. The good O2 sensor circuit will set a new DTC. The other circuit, the one that set the first code, will need to be tested for voltage at the O2 sensor, and leaving the O2 sensor. If the O2 sensor output does not change with the other side, replace the O2 sensor. If the voltage changes are a match, then find where the break in continuity is along the wire.