P249D
Closed Loop Reductant Injection Control At Limit Flow Too Low
With reductant injection running closed-loop the controller drives the dosing valve to maximum opening but cannot reach the required AdBlue flow.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: 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)
Common causes
Ordered by how often each turns out to be the cause.
- Reductant pump pressure lowCommon
Parts involved
- Reductant Injector
- Reductant Pump
P249D is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.