P0161: Oxygen Sensor Heater Circuit Malfunction (Bank 2, Sensor 2)

written by Edmunds.com^{This story was created with generative AI and was reviewed and fact-checked by our staff of editors and experts.}
edited by Nick Yekikian^{Senior News Editor
Nick Yekikian has worked in the automotive industry since 2019. He has written close to a thousand car-related articles and tested and reviewed more than 200 vehicles over the course of his career. Nick is the Senior News Editor at Edmunds and has also contributed to MotorTrend, Automobile Magazine and Super Street. When Nick isn't zipping around town in his latest used-car find, he's probably making digital art in Photoshop or playing disc golf with friends.}
1/24/2025
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What does error code P0161 mean?

The P0161 diagnostic trouble code (DTC) stands for "Oxygen Sensor Heater Circuit Malfunction (Bank 2, Sensor 2)." This code is triggered when the engine control module detects a problem in the oxygen sensor's heater circuit, located downstream of the catalytic converter on Bank 2. The heater sensor ensures the engine reaches optimal operating temperature quickly for accurate readings.

Why is P0161 important?

The oxygen sensor heater ensures proper fuel-air mixture management in the engine. A malfunctioning heater circuit can lead to delayed sensor operation, which can cause inefficient fuel combustion, increased emissions and reduced engine performance. Additionally, unresolved issues with the oxygen sensor heater may cause the vehicle to fail emissions tests.

Can I safely drive my car with this error code?

Driving with the P0161 code is possible but not recommended. While it may not immediately affect drivability, prolonged operation with a faulty sensor heater circuit can reduce fuel efficiency, increase emissions and potentially damage the catalytic converter.

Common symptoms of P0161 error code

Illuminated check engine light
Decreased fuel efficiency
Increased exhaust emissions
Failed emissions test

How is error code P0161 diagnosed?

Diagnosing P0161 involves the following steps:

Scan for codes: Use an OBD-II scanner to confirm the P0161 code and identify related codes.
Inspect wiring and connectors: Check for damage, corrosion or loose connections in the oxygen sensor heater circuit.
Test the sensor heater resistance: Use a multimeter to measure the heater circuit’s resistance. A reading outside the manufacturer's specifications indicates a problem.
Check voltage supply and ground: Verify that the heater circuit receives proper voltage and ground signals from the engine control module.
Evaluate engine control module functionality: Rule out engine control module issues that may affect the heater circuit.

How is the P0161 error code repaired?

Clearing the P0161 code typically involves:

Replacing a faulty oxygen sensor.
Repairing or replacing damaged wiring, connectors or components in the heater circuit.
Testing and replacing a malfunctioning engine control module if necessary.
Clearing the code and performing a test drive to confirm the repair.