P23BC
NOx Sensor Calibration Memory Bank 1 Sensor 3
The NOx sensor on bank 1 sensor 3 reports a calibration memory check-sum failure - factory calibration data corrupted or unreadable.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
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
Ordered by how often each turns out to be the cause.
- Calibration memory corruptedCommon
- Module software outdated, reflash may resolveLess likely
- Supply voltage outside specificationLess likely
Parts involved
- NOX Sensor B1s3
P23BC is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.