O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 2)
The heater inside the rear oxygen sensor on bank 2 is not working correctly. This can prevent the sensor from warming up fast enough and may keep the engine light on. It usually affects emissions control more than how the car drives.
You can usually drive short term, but the vehicle may fail emissions testing and fuel control may be affected. Do not ignore it for long because the problem can worsen or hide other exhaust issues.
P0161 means the powertrain control module detected a fault in the heater circuit for the downstream oxygen sensor on bank 2, sensor 2. The heater helps the sensor reach operating temperature quickly so the PCM can monitor exhaust and catalyst efficiency. A fault can be caused by a bad sensor heater, wiring damage, blown fuse, or a control circuit problem.
Bank 2 is the engine side without cylinder 1. Sensor 2 is the downstream oxygen sensor located after the catalytic converter.
No, this code usually does not prevent the engine from starting. It mainly affects emissions monitoring and sometimes fuel control.
Sometimes, but not always. Wiring, fuse, connector damage, or a control issue can also cause this code, so testing first is best.
No. If the fault is still present, the code will return after the system runs its self-test.