Powertrain
generic / SAE
P2BA9
NOx Exceedence — Insufficient Reagent
The SCR system has detected that NOx emissions exceed the legal limit and the cause is traced to insufficient AdBlue/DEF dosing. Modern emission regulations require this fault to be reported separately so that operator-induced misuse (running an empty tank, diluting the fluid) is recorded.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / numberB / A9
Possible causes
- DEF tank repeatedly run empty high
- Diluted or contaminated DEF medium
- Dosing pump output below spec 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)
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 200–1500 €
- Estimated time: 1–4 h
- Component: reductant dosing unit
- Component: reductant tank
- Component: scr catalyst
- MIL / check engine light
- emissions-relevant
- drive cycle required
- limp mode possible
Sources
References
sae:J2012