P249DClosed Loop Reductant Injection Control At Limit - Flow Too Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- With P249D the NOx feedback loop of the SCR system has pushed its long-term correction as far as it may go because the delivered amount of DEF appears too small for the measured NOx. GM's tables judge this via the long-term adaptation value: above 1.69 in the 2014 diesel table and above 1.99 in the 2018 table; both rate it Type B, lamp after the second failing trip. Ford's 2023 diesel summary sets the code when the correction factor sits at its clip for 30 s while the SCR is warm and steady. Typical background is a partly blocked or worn dosing valve, weak pump pressure, crystallised urea or diluted fluid. The mirror code P249E means the loop had to take dosing back to its lower limit. Higher NOx output and possible later power reduction are the practical effects.
- What you may notice
- Malfunction indicator lamp on
- Increased DEF warnings or later speed or power limitation
- SCR efficiency code may follow
- Likely causes
- LikelyDosing valve partly blocked by urea crystals or deposits
- PossibleWeak DEF pump or restricted supply line and filter
- PossibleDiluted or wrong fluid in the DEF tank
- RareNOx sensor reading too high and misleading the controller
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €100 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.