Lost Communication With Battery Energy Control Module "A"

What it means

Another module, usually the hybrid control module, has stopped receiving messages from battery energy control module "A" over the CAN bus. This module monitors the voltage, temperature and charge of the main high-voltage battery on hybrid and electric vehicles, and when it is lost the vehicle usually stops using the battery to protect it. The cause can be simple, such as a weak small auxiliary battery, a fuse or a connector, and several U codes together point to a bus or power problem.

Related codes: U0112U0110U0293P0A80P0562U0001

Symptoms5

• Hybrid system warning light or check system message on.
• Vehicle does not enter ready mode or loses electric power.
• Main battery charge level missing or shown incorrectly.
• Unable to charge on plug-in vehicles.
• Scan tool cannot communicate with the battery management module.

Possible causes6

• Weak small auxiliary battery that powers the control modules.
• Blown module power fuse.
• Loose or corroded connector in the communication wiring near the battery pack.
• Water or moisture entering the battery area, such as under the rear seat or the floor.
• Poor module ground.
• Internal failure of the battery management module.

How to diagnose6

1. Read codes from all modules; if many modules report lost communication, start with the battery and the bus, and if only the battery energy control module "A" is missing, focus on it.
2. Try to communicate with the battery energy control module "A" directly with a scan tool; no response points to lost power, ground or wiring to it.
3. Locate the battery energy control module "A" from the manufacturer information, which on hybrid and electric vehicles is usually inside or next to the main battery pack, and its location and the number of such modules vary by make, then check its power fuse and measure power and ground at its connector.
4. Inspect the module connector for water, corrosion or loose terminals, and check the bus wiring to it.
5. Disconnect the battery and measure resistance between the CAN bus wires at the module connector, comparing with the manufacturer specification to find an open or short.
6. Do not disconnect or touch the orange cables or high-voltage parts; testing and repair need a technician trained on hybrid and electric vehicles.

How to fix6

1. Charge or replace the battery, and clean and tighten its terminals.
2. Replace the blown fuse after finding why it blew.
3. Clean the module connector and repair the ground or damaged bus wiring.
4. Update the module software if the manufacturer has an update.
5. Replace the battery energy control module "A" if proven faulty with good power and bus wiring, then program and code it to the vehicle.
6. Clear codes in all modules and confirm the code does not return.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low for the auxiliary battery, a fuse or a connector, and rises if the battery pack must be opened or its management module replaced and programmed by a specialist.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions