Powertrain
generic / SAE
P221B
NOx Sensor 1/2 Correlation (Bank 2)
NOx sensors 1 and 2 on bank 2 disagree by more than the allowed tolerance over a drive cycle. One sensor drifts, or there is a real NOx gradient that exceeds the calibrated map.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number2 / 1B
Possible causes
- One sensor drifts high
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)
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
- Estimated cost: 300–2000 €
- Estimated time: 1–5 h
- Component: nox sensor
- MIL / check engine light
- emissions-relevant
Sources
References
sae:J2012