O2 Sensor Circuit No Activity Detected (Bank 2, Sensor 3)

The PCM sees no voltage changes from the O2 sensor. It is not responding to exhaust gas changes, indicating it is dead or electrically disconnected.

Yes, if the sensor connector came unplugged or a wire broke, the PCM will see no signal activity.

Yes, the affected O2 sensor monitor will not complete, which can prevent passing an emissions test even after the code is cleared.

The OBD II regulation requires four separate detections for an oxygen sensor (Title 13 CCR 1968.2, section (e)(7.2)): deterioration in voltage, response rate or amplitude that would push emissions past 1.5 times the FTP standards; loss of circuit continuity; out-of-range values; and the case where the sensor has degraded enough that the fuel system stops using it and falls back to open loop. A sensor can therefore set a code while still producing a signal that looks plausible on a scan tool. This is the threshold the monitor is designed around, not a description of your specific fault — the regulation says what the system must detect, not how to find it on your vehicle.