P249D code meaning
Closed Loop Reductant Injection Control At Limit - Flow Too Low
Powertrain system Generic code P24xx codes Check engine light
What P249D means
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.
P249D at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor1 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P249D
- Malfunction indicator lamp on
- Increased DEF warnings or later speed or power limitation
- SCR efficiency code may follow
Common causes of P249D
- Most 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
- Less likelyNOx sensor reading too high and misleading the controller
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Reductant injectorReductant pump
What each part of P249D means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 9D | The exact fault in that area. |
What to do next
- Note P249D and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P249D
What does P249D mean?
P249D means "Closed Loop Reductant Injection Control At Limit - Flow Too Low". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P249D?
Drive gently and only to a workshop. With P249D the car can go into limp mode (reduced power) to protect itself.
Will P249D fail an emissions test?
Yes, it can. P249D is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P249D to fix?
Difficulty: medium. A typical repair takes 1 to 3 hours of work. This is a job for a workshop.
Will P249D clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.