P249C: Excessive Time To Enter Closed Loop Reductant Injection Control

P249C covers the SCR dosing strategy rather than a part: after start-up the engine controller is expected to switch from fixed, map-based urea dosing to dosing corrected by the NOx sensor signal, and this code means that switch happened too seldom or too late. Ford's 2023 diesel summary checks how much of the operating time was really spent in closed loop compared with what was expected, with SCR temperature between 160 and 550 °C, coolant above 70 °C and a 300 s run. Usual reasons are a NOx sensor not yet ready, implausible exhaust temperatures or a cold SCR. P249D and P249E report the opposite case, a loop that runs but has run out of correction range. The driver usually only sees the warning lamp.

Symptoms

• Malfunction indicator lamp on
• Often no noticeable change in driving behaviour
• NOx sensor or exhaust temperature codes may be stored as well

Most likely causes

• Downstream NOx sensor slow to become ready or faulty, so closed loop cannot start
• Implausible exhaust gas temperature signal upstream or downstream of the SCR
• Mostly short or cold trips keep the SCR below its working temperature
• Engine control software calibration requiring an update

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the AdBlue/DEF level and quality, and do not add additives or water
2. Look for white crystals around the injector and the tank
3. Check connectors and heaters with the scanner
4. Run the dosing test available on your diagnostic tool
5. Replace parts only when the test points to that component

Good to know

• Repair difficulty: hard
• It affects emissions.

What each character of P249C means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 4: Emissions
• 9C: Specific fault in that system

Frequently asked questions

Can I keep driving with code P249C?

Deal with it soon. If the instrument cluster shows a countdown, the car may not restart once it reaches zero.

What causes code P249C?

The most common causes are: downstream NOx sensor slow to become ready or faulty, so closed loop cannot start; implausible exhaust gas temperature signal upstream or downstream of the SCR; mostly short or cold trips keep the SCR below its working temperature.

Related codes

• P249DClosed Loop Reductant Injection Control At Limit - Flow Too Low
• P249EClosed Loop Reductant Injection Control At Limit - Flow Too High
• P20EESCR NOx Catalyst Efficiency Below Threshold (Bank 1)
• P202EReductant Injection Valve Circuit Range/Performance (Bank 1 Unit 1)

Sources

• fordservicecontent.com: obd summary diesel 2023
• law.cornell.edu: 13 CCR 1968.2

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.