P0161 Oxygen sensor heater circuit (bank 2, sensor 2)
What P0161 means
The heater element inside the downstream oxygen sensor on bank 2 is not working, or its circuit is broken. The sensor warms up too slowly or not at all, so the catalyst check on that bank cannot run. Bank 2 is the side of a V6, V8 or boxer engine that does not contain cylinder 1.
P0161 is a generic SAE J2012 code: it means the same on every make. The exact cause still depends on the car, so read the freeze-frame data before replacing parts.
At a glance
- Severity
- Medium
- Typical repair cost
- 60–250 €
- Workshop time
- 0.3–1.5 h
- Repair difficulty
- Easy
- DIY possible
- Yes
- Check engine light
- Yes
- Affects emissions test
- Yes
Parts and labour at an independent workshop in Europe. Main dealers charge more; the cause decides the bill, not the code.
Symptoms
- Check engine light on after several drives
- Usually no change in how the car drives
- Catalyst readiness monitor not completing
- Failed emissions inspection
Common causes
- Burnt-out heater element in the downstream oxygen sensor
- Blown fuse or faulty relay in the heater supply
- Broken wire or corroded connector
- Engine control unit heater driver fault (rare)
Can I keep driving with P0161?
You can keep driving, but have it checked within one to two weeks. The engine is not affected, but the car may fail its emissions test.
What to check first
- Check the oxygen sensor heater fuse and relay.
- Inspect the connector and wiring under the car for damage and corrosion.
- Measure the heater resistance at the sensor; an open circuit means the heater has burnt out.
- Check supply voltage with the key on, then replace the sensor if needed.
Related codes
- P0160 Oxygen sensor circuit no activity detected (bank 2, sensor 2)
- P0158 Oxygen sensor circuit high voltage (bank 2, sensor 2)
- P0157 Oxygen sensor circuit low voltage (bank 2, sensor 2)
- P0156 Oxygen sensor circuit (bank 2, sensor 2)
- P0155 Oxygen sensor heater circuit (bank 2, sensor 1)
- P0153 Oxygen sensor slow response (bank 2 sensor 1)
- P0152 Oxygen sensor circuit high voltage (bank 2, sensor 1)
- P0170 Fuel trim malfunction (bank 1)
Data: TORKO fault-code catalogue, built on OBDex (CC0-1.0) and reviewed against workshop practice. Informational only — it does not replace a diagnosis by a mechanic.
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