P249C
Excessive Time To Enter Closed Loop Reductant Injection Control
After cold start the AdBlue injection runs open-loop until SCR temperature is reached. The transition into closed-loop is taking longer than calibrated.
- 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.
- SCR warm-up slowCommon
Parts involved
- SCR Catalyst
- Reductant Injection Control
P249C 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.