The fault code P0161 is a “Malfunction of the Oxygen sensor Heater Circuit” (Bank 2, Sensor 2). Bank 2, Sensor 2 will alert you to an issue with the heater circuit for the oxygen (O2) sensors. Modern oxygen sensors are equipped with heating components that allow them to quickly reach their optimal operating temperature. Engine Control Modules (ECM/PCMs) use data from heated sensors to calculate fuel distribution ratios and monitor catalytic converter performance. The block that contains the second cylinder of the engine is called Bank 2 Sensor 2 is the downstream sensor, located just after the catalytic convertor. This sensor’s primary function is to regulate the amount of oxygen present in exhaust gases leaving the catalytic convert.
The PCM constantly monitors the signals coming from the heated oxygen sensor. The PCM will set codes if there is any suspicious fluctuation or change in voltage signals.
The P0161 only applies to V8 or V6 engines. This code won’t be set if your vehicle has only four cylinders. There will be only one engine bank, and usually only one downstream sensor. A faulty downstream heated sensor will instead set P0141, ‘Oxygen Sensing Heater Circuit Malfunction Bank 1, Sensor 2’.
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What are the possible causes of fault code P0161?
The PCM can set the P0161 error code for several reasons:
- Faulty oxygen sensors (Bank 2, Sensor 2)
- Problems with the oxygen sensor heating circuit (open circuit or short circuit or high resistance)
- A problem with the PCM
What are the symptoms of fault code P0161?
The code P0161 may not cause any symptoms,
- This code may only cause the engine fault lamp to illuminate
- Increased emissions values
How to Fix Fault Code P0161?
- Repairing the cable in the heating circuit
- Replace the Bank 2 Sensor 2 oxygen sensor
How serious is fault code P0161?
The fault code P0161 has no effect on the driving ability of the vehicle. It may, however, cause the emission values to increase. Ignoring a fault too long can damage the catalytic convertor. A continuously lit engine fault light can also mislead the driver as to other fault codes that are developing. It should therefore be repaired at the appropriate time.
