O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 3)

Yes, you can drive normally. The sensor 3 heater failure only affects how quickly the sensor reaches operating temperature. It does not affect engine performance.

No. P0147 is a low-severity code. The only consequence is a Check Engine Light, possible emissions test failure, and slightly higher emissions during cold operation. Schedule the repair at your convenience.

Yes, if you can access it under the vehicle. It requires an O2 sensor socket (22mm) and some penetrating oil if the sensor is seized. The sensor is typically located after the second catalytic converter.

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.