OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P2BA8

NOx Exceedence - Interruption of Reagent Dosing Activity

NOx emissions are above the legal threshold and the ECU isolates the cause to interruption of reductant dosing. The injection valve, pump, or supply line is impaired.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / numberB / A8

Possible causes

  • Reductant injection valve clogged high
  • Reductant pump output insufficient 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: 1–8 h
  • Component: reductant injection valve
  • Component: reductant pump
  • Component: scr module
  • MIL / check engine light
  • emissions-relevant
  • drive cycle required
  • limp mode possible

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication