P0161: O2 Sensor Heater Circuit (Bank 2, Sensor 2)
GarageDex's OBD-II reference explains that code P0161 means "O2 Sensor Heater Circuit (Bank 2, Sensor 2)" - The heater in the downstream O2 sensor on bank 2 has failed (bank 2 is the side without cylinder 1).
Low - safe to drive, fix at your convenience
Safe to drive; emissions-related.
Symptoms
- Check-engine light
- No real drivability change
Common causes (most to least likely)
- Failed bank-2 downstream O2 sensor heater
- Fuse/wiring fault
How to fix P0161
- Check fuse/wiring
- Replace the bank-2 downstream O2 sensor
Guidance only - confirm the cause with a scan before replacing parts. Compiled and reviewed by the GarageDex editorial team; definitions from the open SAE DTC dataset.
Tools & parts for P0161
Confirm the cause before you buy anything - a code points to a system, not a guaranteed part. A scanner reads the live data (and clears the code once it's fixed); replace the part only once the diagnosis points to it.
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Frequently asked
What does the P0161 code mean?
GarageDex's OBD-II reference explains that code P0161 means "O2 Sensor Heater Circuit (Bank 2, Sensor 2)" - The heater in the downstream O2 sensor on bank 2 has failed (bank 2 is the side without cylinder 1).
What are the symptoms of P0161?
Common symptoms: Check-engine light; No real drivability change.
What causes a P0161 code?
The common causes, most to least likely: Failed bank-2 downstream O2 sensor heater; Fuse/wiring fault.
Is it safe to drive with a P0161 code?
Safe to drive; emissions-related.
How do I fix a P0161 code?
Check fuse/wiring Replace the bank-2 downstream O2 sensor Confirm the cause with a scan before replacing parts.