P0161O2 Sensor Heater Circuit Bank 2 Sensor 2
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- The downstream oxygen sensor on bank 2 (sensor 2) has an electric heater so that it reaches working temperature quickly. P0161 concerns this heater circuit and its performance. GM measures the current through its low-side driver and fails it outside 0.3–2.9 A on the supercharged V8 (8 of 10 samples, two trips). Ford checks the driver voltage continuously and the current once per drive cycle once the sensor is estimated above about 120 °C; the lower limit is 0.22–0.55 A depending on sensor type, the upper 3 A. Without heat the sensor becomes active late or not at all, so P0159/P0160 can follow; there is no limp mode.
- What you may notice
- Check engine light on (usually after two drive cycles)
- Follow-up codes P0159/P0160 possible
- Catalyst monitor readiness for bank 2 not set
- Likely causes
- LikelyHeater element of the sensor burnt out
- PossibleHeater wiring, connector or fuse open or corroded
- RareShort in the heater circuit (current too high)
- RareDriver in the engine module faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €60 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.