P224B: NOx Sensor Heater Resistance (Bank 1 Sensor 2)
Standardized SAE J2012 code · P22xx — Fuel & air metering and auxiliary emission controls
What does P224B mean?
The measured heater element resistance of the NOx sensor on bank 1 sensor 2 is outside the calibrated range. Used as a sensor-element health check.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Common causes
- High Heater element aged
Likelihood is a general estimate across vehicles; your make and model may differ.
Add your car to see reports of P224B on the same make and model first.
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