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

P2BAE

NOx Exceedence - EGR System

NOx emissions are above the legal threshold and the ECU isolates the cause to the EGR system. EGR flow is too low or absent under operating conditions where NOx reduction is required.

SystemPowertrain
Typegeneric / SAE
GroupP2
Range / numberB / AE

Possible causes

  • EGR valve stuck closed high
  • Carbon clogged EGR passages high

Symptoms

  • Check engine light on
  • Pinging or knocking under load
  • Power loss and hesitation
  • Possible rough idle
  • Failed emissions inspection (NOx)

Inspection / repair

  • Difficulty: hard
  • DIY: shop recommended
  • Estimated cost: 300–1800 €
  • Estimated time: 1.5–6 h
  • Component: egr valve
  • Component: egr cooler
  • Component: egr diff pressure sensor
  • 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