Powertrain, generic (extended)

P2BA8 NOx Exceedence - Interruption of Reagent Dosing Activity

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

With P2BA8 the controller states that NOx went up because reagent dosing stopped although the engine needed it. Regulation (EU) 2017/1151 Annex XVI, point 5.5, treats such an interruption as a case for the driver warning, unless the system paused dosing on purpose in conditions the maker declared to the authority; if dosing is not restored within 50 km, inducement starts. In California, section (f)(2.2.3)(A) of the OBD rule requires reagent delivery to be monitored. No maker documents P2BA8 publicly. The component fault behind the stop, such as pump P208B, pressure P20E8 or injector P2047, usually sets its own code; P2BA8 marks the emission consequence, while P2BA7 covers an empty tank and P2BAA too little consumption.

Likely causes

DEF injector clogged or stuck by crystals
Pump failure or pressure not built up
Frozen fluid because tank or line heater fails
Wiring or SCR control unit fault stopping dosing

Symptoms

  • DEF dosing malfunction message with distance countdown
  • MIL on, further SCR component codes stored
  • Reduced power or no restart if not repaired

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–1,500
Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

reductant injection valvereductant pumpscr module

Related codes

P208BP20E8P2047P2BA7P2BAA

References: legislation.gov.uk, law.cornell.edu.