OBD-II code · Powertrain (generic, extended)
P2221 NOx Sensor Heater Sense Circuit (Bank 2)
NOx Sensor Heater Sense Circuit (Bank 2): an electrical fault is present in the circuit. The NOx sensor heater brings the sensor to operating temperature; a fault delays accurate NOx readings used for SCR control.
Is it safe to drive with P2221?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySense circuit failed
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)
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–3 h
- Emissions test
- Likely to fail
- Parts involved
- Nox Sensor
Related codes
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.