Failed or internally shorted reductant control module, often due to fluid intrusion or heat damage; Corroded, loose, or damaged electrical connector at the reductant control module; Open or shorted CAN bus wiring between the ECM and the reductant control module; Blown fuse or poor ground connection supplying power to the reductant control module; Low battery voltage or a weak charging system causing the module to drop offline intermittently; Software corruption or a failed module reflash that leaves the reductant module unresponsive; Aftermarket accessories or poor previous repairs that disturb the CAN bus wiring harness

DTC codes / U01xx · Lost communication with a control module / U010E

U010ELost Communication With Reductant Control Module

Q: What does code U010E mean?

Lost Communication With Reductant Control Module. U010E is a generic network communication code indicating that the engine control module (ECM) has lost contact with the reductant control module, which manages the diesel exhaust fluid (DEF) system on diesel vehicles. The ECM monitors a controller area network (CAN) bus for regular status messages from the reductant module, and when those messages stop arriving for a calibrated time, it stores this code and typically illuminates the check engine light.

U010E is a generic network communication code indicating that the engine control module (ECM) has lost contact with the reductant control module, which manages the diesel exhaust fluid (DEF) system on diesel vehicles. The ECM monitors a controller area network (CAN) bus for regular status messages from the reductant module, and when those messages stop arriving for a calibrated time, it stores this code and typically illuminates the check engine light.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaLost communication with a control module

Symptoms you may notice

Illumination of the check engine light or service engine soon light, often with no other noticeable symptoms
A message on the driver information center indicating a DEF system fault or that the vehicle will soon be speed-limited
Reduced engine power or a limp-home mode if the fault persists and the ECM derates the engine
Inability to clear the code permanently because communication is still missing
Other warning lights such as glow plug or emissions-related lamps may accompany the check engine light
On some vehicles, the engine may refuse to restart after shutdown once the fault is active

Common causes, most likely first

Failed or internally shorted reductant control module, often due to fluid intrusion or heat damage
Corroded, loose, or damaged electrical connector at the reductant control module
Open or shorted CAN bus wiring between the ECM and the reductant control module
Blown fuse or poor ground connection supplying power to the reductant control module
Low battery voltage or a weak charging system causing the module to drop offline intermittently
Software corruption or a failed module reflash that leaves the reductant module unresponsive
Aftermarket accessories or poor previous repairs that disturb the CAN bus wiring harness

How to diagnose and fix it

Perform a full battery and charging system test to rule out low voltage as the root cause of the communication loss
Inspect the reductant control module connector and harness for corrosion, pushed pins, or chafed wires, and clean or repair as needed
Check all fuses and grounds that feed the reductant control module, verifying power and ground at the module connector with a multimeter
Use a scan tool to check for communication with the reductant module on the CAN bus and perform a network integrity test if supported
Measure CAN bus resistance and voltage at the module connector to confirm the bus is intact and not shorted or open
If wiring and power are good but the module does not respond, substitute a known-good module or perform a module reflash per manufacturer procedure
After repair, clear codes and verify communication is restored, then complete any required DEF system relearn or adaptation drive cycle

What most technicians overlook on U010E

A weak or failing battery is a frequent culprit because the reductant control module may boot slowly or drop offline during cranking, setting a communication code without any hard wiring fault.
The code can be set by a completely unrelated module on the same CAN bus that is shorting the network, so checking bus voltage and resistance before condemning the reductant module saves unnecessary parts replacement.
Some vehicles require a software update to the ECM or reductant module to correct a known communication dropout, and replacing the module without checking for bulletins will not fix the root cause.
Corrosion inside the reductant module connector is common on vehicles that operate in wet or salty conditions, and the pins can look clean until the connector is disassembled and inspected closely.
U010E does not always mean the reductant module is dead; a blown fuse shared with another circuit or a poor ground can leave the module unpowered while the module itself is perfectly functional.

Can I keep driving with U010E?

You can usually drive the vehicle short distances to a repair shop, but avoid long trips or heavy loads because the ECM may derate engine power or prevent restart once the fault is active. If the vehicle enters limp mode or displays a speed-limiting warning, stop driving and arrange a tow to prevent unsafe operation.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.