U040FInvalid Data Received From Reductant Control Module
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- On a diesel with SCR, the reductant control module looks after the urea circuit, chiefly the pump, dosing and heater control, and reports pressure and status to the engine controller. U040F means its messages arrive but fail validation. GM's 2025 ECM tables check counter and checksum of the DEF information and dosing status frames, count 6 errors among 15 or 3 among 10 checks as a failure; the result is Type A with the MIL on trip one. Ford's 2023 diesel OBD summary groups U040F with the functional test of the reductant pump motor and sets it when the duty-cycle control signal of the pump motor controller leaves the 4 to 96 percent window, next to pump speed, voltage and temperature codes. Without trusted module data dosing is stopped, NOx rises and the inducement strategy may later limit speed. U010E is lost contact.
- What you may notice
- Check engine light
- DEF/AdBlue warning with countdown to a speed limit
- Further SCR or reductant pump codes stored
- Likely causes
- PossiblePump motor controller in the reductant module reporting an invalid control signal
- PossibleCorroded connector or damaged bus line at the tank-mounted module
- PossibleSoftware of the reductant module or ECM out of step
- RareReductant control module internally faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.