What it means
Same as P249D with the controller fully closing the dosing valve yet still measuring more flow than needed - the valve does not seat fully.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The reductant dosing system meters AdBlue/DEF into the exhaust for NOx reduction in the SCR catalyst. In closed-loop operation, the controller can reduce dosing by closing the valve; P249E sets when it reaches that limit but measured flow stays above the requested amount, pointing to excess flow or a misleading flow reading.
Common causes
Most likely first.
- Dosing valve leaking or failing to close
- Debris or crystallized reductant preventing valve seating
- Faulty reductant flow sensor
- Damaged wiring or connector at the dosing valve
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)
How to diagnose it
- Review freeze-frame data and live commanded versus measured reductant flow to confirm that excess flow occurs while the dosing valve is commanded closed.
- Inspect the dosing valve and injector for crystallized reductant or debris that could prevent the valve from seating.
- Check the valve body, fittings, and reductant line for damage or signs of leakage that could allow unintended delivery.
- Inspect the dosing valve connector and wiring for corrosion, loose pins, or damage that could interfere with valve control.
- Use the scan tool's available actuator test to check whether the valve responds to open and closed commands.
- Compare flow sensor readings with the manufacturer's diagnostic procedure and test the sensor circuit before replacing the sensor or valve.
Common fixes
- Clean deposits from the dosing valve if the manufacturer's service procedure permits it.
- Repair damaged wiring or a loose or corroded valve connector.
- Replace a dosing valve that fails to close or is mechanically damaged.
- Replace a faulty flow sensor after its readings and circuit have been checked.
Can I keep driving?
Avoid extended driving until the excess dosing is diagnosed; incorrect reductant delivery can disrupt emissions control and may lead to AdBlue warnings or a no-start countdown. If the warning countdown appears, follow the vehicle's instructions promptly.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.