P2BA7
NOx Exceedence - Empty Reagent Tank
NOx emissions are above the legal threshold and the ECU isolates the cause to an empty reductant tank. SCR cannot dose AdBlue/DEF.
- 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.
- DEF/AdBlue tank empty - refill requiredCommon
- Level sensor reads empty incorrectlyPossible
Parts involved
- Reductant Tank
- Reductant Level Sensor
P2BA7 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.