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DTC codes / U01xx · Lost communication with a control module / U014A

U014ALost Communication With Battery Energy Control Module C

U014A indicates that the vehicle's control modules have lost communication with the Battery Energy Control Module C (BECM C), which is the controller responsible for monitoring and managing the high-voltage battery pack in hybrid and electric vehicles. The code is set when the module that expects regular status messages from the BECM C stops receiving them within the required time window, often due to a wiring fault, power loss, or internal module failure.

SystemNetwork
Code typeGeneric (all makes)
SeverityHigh
Fix difficultyProfessional
AreaLost communication with a control module

Symptoms you may notice

  • Illumination of the check engine light, service vehicle soon, or high-voltage system warning lamp.
  • Reduced power output or a 'limp home' mode as the vehicle limits operation to protect the battery.
  • The vehicle may fail to start or enter 'ready' mode if the high-voltage battery management is unavailable.
  • Inconsistent state-of-charge readings or sudden drops in range on the dashboard display.
  • Often no symptoms besides the warning light, especially if the communication loss is intermittent.
  • Other unrelated warning lights may appear due to cascading communication errors on the CAN bus.

Common causes, most likely first

  1. Damaged, corroded, or disconnected wiring or connectors in the CAN bus circuit between the BECM C and other modules.
  2. Blown fuse or poor power/ground connection to the BECM C, causing the module to be inoperative.
  3. Internal failure of the BECM C itself, often due to heat, vibration, or component degradation.
  4. Software or firmware corruption in the BECM C requiring reflash or replacement.
  5. A fault in another module on the same CAN segment that disrupts communication, such as a shorted transceiver.
  6. Water intrusion or physical damage to the BECM C housing or its harness.
  7. Low 12-volt battery voltage causing modules to drop offline intermittently.

How to diagnose and fix it

  1. Verify the 12-volt battery is fully charged and in good condition, as low voltage can cause communication codes.
  2. Inspect the BECM C harness and connectors for corrosion, loose pins, or chafed wires, and repair as needed.
  3. Check all fuses and relays that supply power to the BECM C, and confirm good grounds.
  4. Use a scan tool to perform a network communication test and identify which modules are offline.
  5. Measure CAN bus resistance and voltage to rule out a short or open circuit on the communication lines.
  6. If wiring and power are good, reflash or replace the BECM C following manufacturer procedures, including any required programming.
  7. Clear codes and perform a road test to confirm the communication loss is resolved and no new codes appear.

BECM Communication Faults You Should Not Overlook

  • A common misdiagnosis is replacing the BECM C when the real fault is a corroded connector or a chafed wire in the high-voltage harness, so always perform a thorough visual and electrical inspection first.
  • Intermittent U014A codes often appear after a low 12-volt battery event or jump start, and they may clear on their own after the battery is recharged and the system stabilizes.
  • The BECM C is sometimes integrated into the battery pack assembly, and communication loss can be caused by a failing cell module that disrupts the internal network, not just the external wiring.
  • Other modules on the same CAN bus can set U014A as a secondary code if they are the ones actually losing communication, so check for additional codes that point to the root cause.
  • High-voltage system safety procedures must be followed when inspecting BECM C wiring; never probe connectors without proper personal protective equipment and training.

Can I keep driving with U014A?

Do not continue driving with U014A set, because the vehicle may enter a reduced-power mode or shut down unexpectedly, and the high-voltage battery could be operated without proper monitoring. Have the vehicle inspected by a qualified technician, especially if any high-voltage warning is present.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

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

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