P2BAF
NOx Sensor Heater Sense Circuit Range/Performance Bank 1 Sensor 1
The heater sense feedback of NOx sensor 1 on bank 1 reports values that do not match expected operation. The sensor warm-up cycle does not behave as the diagnostic expects.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
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.
- NOx sensor agingCommon
- High resistance in heater circuitPossible
- Sensor element aged beyond calibration windowLess likely
Parts involved
- NOX Sensor
- NOX Heater Circuit
P2BAF 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.