Damaged, corroded, or loose wiring or connector pins in the CAN bus circuit between the battery interface module and the network; Failed Hybrid/EV Battery Interface Control Module O itself, often due to internal electronics failure; Low or unstable 12-volt supply to the battery interface module, such as a weak battery or poor ground; Open or shorted CAN bus wiring caused by chafing, rodent damage, or water intrusion; A faulty gateway module or network termination issue that disrupts communication on the bus segment; Software or calibration fault in the battery interface module requiring reprogramming; Aftermarket accessories improperly tapped into the CAN bus wiring

DTC codes / U01xx · Lost communication with a control module / U01AE

U01AELost Communication With Hybrid/EV Battery Interface Control Module O

U01AE is a generic network communication code indicating that one or more control modules have lost the CAN (Controller Area Network) data link with the Hybrid/EV Battery Interface Control Module O. The module that set the code expected a regular heartbeat message from the battery interface module and stopped receiving it, so it flagged the missing communication.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaLost communication with a control module

Symptoms you may notice

Illumination of the check engine light, service vehicle soon message, or hybrid system warning lamp
The vehicle may enter a reduced-power or limp mode with limited hybrid operation
No noticeable drivability symptoms besides the warning light in some cases
Failure of the high-voltage battery to accept or deliver charge, or the engine failing to auto-stop
Intermittent dashboard warnings that come and go with temperature or vibration
Other unrelated modules may log communication codes or show erratic behavior

Common causes, most likely first

Damaged, corroded, or loose wiring or connector pins in the CAN bus circuit between the battery interface module and the network
Failed Hybrid/EV Battery Interface Control Module O itself, often due to internal electronics failure
Low or unstable 12-volt supply to the battery interface module, such as a weak battery or poor ground
Open or shorted CAN bus wiring caused by chafing, rodent damage, or water intrusion
A faulty gateway module or network termination issue that disrupts communication on the bus segment
Software or calibration fault in the battery interface module requiring reprogramming
Aftermarket accessories improperly tapped into the CAN bus wiring

How to diagnose and fix it

Perform a full system scan with a capable scan tool to confirm U01AE is current and check for related communication codes in other modules
Inspect the 12-volt battery condition, terminals, and the ground connections serving the hybrid battery interface module
Visually inspect the CAN bus wiring and connectors at the battery interface module for corrosion, looseness, or damage
Measure CAN bus resistance and voltage levels to verify the bus is not shorted or open, following the manufacturer's network diagnostic procedure
Check for power and ground at the battery interface module connector with the key on
If wiring and power are good, substitute a known-good module or perform a module communication test to confirm the module is at fault
Repair or replace the faulty wiring or module, then clear codes and verify communication is restored with a road test

Why the battery module goes silent

A weak or failing 12-volt battery is a common hidden cause of this code because the hybrid battery interface module may boot but drop off the CAN bus under low-voltage conditions.
Water intrusion into the hybrid battery compartment or connector seals can corrode pins and cause intermittent loss of communication that only appears in damp weather.
The code does not always mean the battery interface module is dead; a single chafed CAN wire or a loose ground can set the same code and be far cheaper to fix.
Other modules on the same bus segment can set U01AE if the gateway module is faulty, so always check for communication codes across the entire network before condemning the battery module.
Aftermarket alarms or phone chargers tapped into the CAN wiring can introduce noise or a short that mimics a failed module, so inspect for non-factory wiring first.

Can I keep driving with U01AE?

The vehicle may still drive, but hybrid battery management and charging could be compromised, so limit driving to a short distance to a repair shop and avoid heavy electrical loads or long trips until the fault is diagnosed.

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.