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
| No. | Cause |
|---|---|
| 01 | EGR valve stuck or clogged |
| 02 | EGR cooler blocked |
| 03 | air-mass meter fault |
| 04 | EGR wiring fault |
What to check, step by step
- 01Read EGR-related codes and live data (EGR position, air mass).
- 02Inspect and clean or replace the EGR valve.
- 03Check the air-mass meter and intake leaks.