A weak or dead battery, or poor battery terminal connections, causing low voltage that drops the EGR module offline.; Corroded, loose, or damaged wiring or connectors at the EGR control module or along the CAN bus harness.; A failed EGR control module, often due to internal circuit board faults or water intrusion into the module housing.; Open or shorted CAN bus wires (CAN high or CAN low) between the ECM and the EGR module, including chafed harness sections.; A blown fuse or faulty relay that supplies power to the EGR control module, leaving it unpowered.; A faulty ground connection for the EGR module, causing intermittent or complete loss of communication.; Less commonly, a software or calibration issue in the ECM or EGR module that disrupts message timing.

DTC codes / U01xx · Lost communication with a control module / U010A

U010ALost Communication With Exhaust Gas Recirculation Control Module A

U010A indicates that the engine control module (ECM) or another primary controller has lost the controller area network (CAN) communication link with the exhaust gas recirculation (EGR) control module A. The ECM sets this code after detecting that expected periodic messages from the EGR module have stopped arriving within a calibrated timeout window, not necessarily that the EGR valve itself has failed.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaLost communication with a control module

Symptoms you may notice

Illumination of the check engine light or service engine soon lamp, often with no other symptoms besides the warning light.
The engine may enter a reduced-power or limp-home mode with limited acceleration on some vehicles.
Rough idle, hesitation, or poor fuel economy if the EGR module also controls other engine functions.
Intermittent stalling or hard starting when communication is lost during engine operation.
Other dashboard warning lights may illuminate if the lost module shares a network segment with other controllers.
No noticeable performance change on vehicles where the EGR module only reports emissions data and the ECM defaults to a fixed EGR strategy.

Common causes, most likely first

A weak or dead battery, or poor battery terminal connections, causing low voltage that drops the EGR module offline.
Corroded, loose, or damaged wiring or connectors at the EGR control module or along the CAN bus harness.
A failed EGR control module, often due to internal circuit board faults or water intrusion into the module housing.
Open or shorted CAN bus wires (CAN high or CAN low) between the ECM and the EGR module, including chafed harness sections.
A blown fuse or faulty relay that supplies power to the EGR control module, leaving it unpowered.
A faulty ground connection for the EGR module, causing intermittent or complete loss of communication.
Less commonly, a software or calibration issue in the ECM or EGR module that disrupts message timing.

How to diagnose and fix it

Perform a battery and charging system test first, including load testing the battery and checking for voltage drops at the terminals.
Inspect the EGR control module connectors and harness for corrosion, loose pins, or chafed wires, and clean or repair as needed.
Check all fuses and relays that feed the EGR control module, and verify power and ground at the module connector with a multimeter.
Use a scan tool to check for communication with the EGR module and perform a CAN bus voltage test (approximately 2.5 volts on both CAN high and CAN low with the key on).
If communication is still missing, disconnect the EGR module and check resistance and continuity on the CAN bus wires between the ECM and the module.
Substitute a known-good EGR control module only after confirming power, ground, and bus integrity, then clear codes and verify communication.
After repair, clear all codes and perform a road test to confirm the U010A code does not return and that the EGR monitor completes.

Why the EGR Module Goes Silent

A common oversight is replacing the EGR valve itself when the fault lies in the control module or its power supply, since the valve and module are often separate components.
Low system voltage from a failing battery or alternator frequently causes communication codes like U010A before any other symptom appears, so always load-test the battery first.
Water intrusion into the EGR module connector or housing is a frequent cause on vehicles that see road spray or steam cleaning, and it can mimic a failed module.
The code can set intermittently due to a poor ground connection that only breaks down under vibration or temperature changes, so wiggle-testing the harness while monitoring live data is essential.
U010A does not always mean the EGR module is defective; a single failed message or a brief voltage dip during cranking can set the code, and it may not return after clearing.

Can I keep driving with U010A?

You can usually drive the vehicle with U010A, but expect reduced engine performance or limp-home mode on some models, and avoid long trips or heavy loads until the fault is diagnosed. If the engine runs poorly or stalls, stop driving and have the vehicle inspected promptly.

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.