This code indicates that the engine computer is seeing no signal activity from the downstream oxygen sensor on bank 2, which is the sensor after the catalytic converter. It usually means the sensor circuit is open, the sensor has failed internally, or the wiring/connector is not completing the circuit. It is not an indication of a rich or lean condition, but rather that the sensor is electrically dead or disconnected.
The sensor itself has an internal open circuit or the sensing element has failed, producing no voltage signal to the computer.
Chafed, broken, or melted wiring, or a corroded/pushed-back pin in the sensor connector, can interrupt the signal or heater circuit.
If the sensor connector was unplugged during other repairs and not reconnected, the computer will see no activity.
A significant exhaust leak upstream of or around the sensor can prevent it from producing a valid signal, though this more often causes slow response codes.
The oxygen sensor heater circuit often shares a fuse; if that fuse is open, the sensor may never warm up and produce a signal.
Extremely rare; the internal input circuit for that specific sensor could be damaged, but this should only be considered after all wiring and the sensor are verified good.
Usually yes, as the downstream sensor primarily monitors catalyst efficiency and does not control fuel mixture. However, the check engine light will stay on and you may fail an emissions test.
No. This code means the sensor signal is electrically absent, not that the catalyst has failed. Catalyst efficiency codes are different.
Almost never. The vast majority of cases are a failed sensor, wiring issue, or fuse. PCM failure is exceptionally rare and should only be suspected after the sensor and wiring are conclusively proven good.
No. Sensor 2 is downstream of the catalytic converter. Bank 2 refers to the side of the engine opposite bank 1, which is usually identified by cylinder 1's location.