OBD-II code · Powertrain (generic, extended)
P2BAD NOx Exceedence - Insufficient Reagent Consumption
The aftertreatment system detects elevated NOx emissions while reagent (AdBlue/DEF) consumption is below the expected level. Causes include clogged dosing injector, incorrect dosing rate or tampering.
Is it safe to drive with P2BAD?
The car may go into limp mode (reduced power). Get it diagnosed before a long trip.
Common causes
- Most likelyClogged DEF dosing valve
- PossibleIncorrect dosing calibration
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)
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–5 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Def Dosing Valve, Scr Catalyst, Nox Sensor
Related codes
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.