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OBD-II · Engine and powertrain (P)

P2BAB

NOx exceedance - incorrect EGR flow

What it means

NOx emissions may exceed limits because exhaust gas recirculation (EGR) flow is wrong. On vehicles with SCR, a confirmed unresolved fault may trigger reduced performance or a no-restart countdown; follow the displayed warning and the vehicle handbook.

Symptoms

  • emissions warning; an AdBlue no-start countdown may appear on SCR-equipped vehicles
  • engine warning light
  • if a no-start countdown is displayed, restarting is inhibited when it reaches zero

Likely causes, most likely first

Likely causes, most likely first
No.Cause
01EGR valve stuck or clogged
02EGR cooler blocked
03air-mass meter fault
04EGR wiring fault

What to check, step by step

  1. 01Read EGR-related codes and live data (EGR position, air mass).
  2. 02Inspect and clean or replace the EGR valve.
  3. 03Check the air-mass meter and intake leaks.