Powertrain
generic / SAE
P2BAC
NOx Exceedence - Insufficient Reagent Quality
The diesel exhaust aftertreatment system detects elevated NOx levels combined with abnormal reagent (AdBlue/DEF) consumption, indicating that the reagent quality is insufficient or contaminated. Many regions trigger driver inducement (limited restarts).
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / numberB / AC
Possible causes
- Non-DEF liquid in tank (water, diesel) high
- Aged or diluted DEF/AdBlue 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: hard
- DIY: shop recommended
- Estimated cost: 200–2000 €
- Estimated time: 1–6 h
- Component: scr catalyst
- Component: def tank
- Component: nox sensor
- Component: def quality sensor
- MIL / check engine light
- emissions-relevant
- drive cycle required
- limp mode possible
Sources
References
sae:J2012