U0111 on Mercedes-Benz
Lost Communication With Battery Energy Control Module "A"
U0111 on Mercedes-Benz vehicles indicates lost communication with battery energy control module "a". Au7o has documented this code across 4 Mercedes-Benz models — most commonly on EQE, EQS, EQS SUV. Sets when a module loses data-bus communication with Battery Energy Control Module 'A' (the high-voltage battery management controller) and no longer receives its expected messages.
Common Causes of U0111
- •Open or shorted bus wiring to the battery energy control module
- •Corroded or loose connector / poor ground
- •Blown fuse / lost low-voltage power feed
- •Low 12V battery voltage
- •Failed battery energy control module
U0111 on Mercedes-Benz by Model
Mercedes-Benz EQE(1 issue)
- Battery Management System Memory Overflow Opens HV Contactors — Sudden Loss of Drive Power2023-2025
Other control units on the EVA2 platform continuously send diagnostic requests to the high-voltage battery management system (BMS). The BMS memory capacity overflows, the module shuts down and commands the HV contactors open, disconnecting the 90.6 kWh pack from the drive unit. The car loses propulsion without warning while driving; steering and brakes remain but power assist behavior changes. NHTSA campaign 24V-372 covers 14,912 EQE/EQS vehicles built roughly Feb 1 2023 - May 11 2024.
Mercedes-Benz EQS(1 issue)
- Battery Management System Software Overload Triggers High-Voltage Shutdown (NHTSA 24V372000)2022-2025
On a large population of EQ vehicles, continuous diagnostic requests from other onboard control units can overload the battery management system's (BMS) memory capacity. This causes the BMS to open the high-voltage contactors, disconnecting the battery pack from the powertrain and producing a sudden loss of drive power. Mercedes-Benz USA recalled 14,912 EQE/EQS/EQE SUV/EQS SUV vehicles in June 2024 (NHTSA campaign 24V372000). Unlike many EQ software fixes, this remedy could not be delivered over the air and required a dealer visit, making it a recurring frustration for owners. The same BMS software is used on EU-spec cars.
Mercedes-Benz EQS SUV(1 issue)
- Battery Management System Diagnostic Memory Overflow Opens HV Contactors (Turtle Mode)2023-2025
Other control units on the EVA2 bus continuously send diagnostic requests to the high-voltage battery management system. The BMS memory overflows, the module shuts down, and the HV contactors open - disconnecting the 108 kWh pack from the drive unit. The result is an instant loss of propulsion at speed with the red turtle icon on the display, even with a nearly full state of charge. NHTSA recall 24V-372 covered 14,912 EQE/EQS sedans and SUVs, and owners reported the failure occurring on freeways before the fix.
Mercedes-Benz GLB(1 issue)
- 48-Volt Lithium-Ion Battery Reinitialization Communication Fault Draining the 12V Battery (Service Campaign 2025100004)2024-2026
The facelifted GLB (2024 onward) gained a 48-volt mild-hybrid system with a second-generation belt-driven starter-generator (RSG), so the car now depends on a small 48V lithium-ion battery for engine restarts, coasting, and recuperation in addition to the conventional 12V battery. Owners on the MBWorld GLB forum report repeated 12V battery discharge - dead or weak battery after short periods parked, requiring frequent jump starts or a tender. Mercedes-Benz opened service campaign 2025100004 (late October 2025) to update the 48-volt on-board electrical system battery software, because a communication error can occur when the 48V lithium-ion battery is reactivated during reinitialization; the same campaign covers CLA and GLA. When the 48V system fails to hand off correctly the 12V side carries loads it was never sized for, which is why the visible symptom is a flat 12V battery rather than a hybrid warning. Separately, GLB owners across model years report the small 1.2 Ah auxiliary battery plus short-trip driving leaves the 12V battery chronically undercharged.
Looking for U0111 on a different make?
View U0111 across all makes →Frequently Asked Questions
What does U0111 mean on Mercedes-Benz?▼
U0111 stands for "Lost Communication With Battery Energy Control Module "A"." Sets when a module loses data-bus communication with Battery Energy Control Module 'A' (the high-voltage battery management controller) and no longer receives its expected messages. On Mercedes-Benz specifically, this code is documented across 4 models.
What causes U0111 on Mercedes-Benz vehicles?▼
Common causes on Mercedes-Benz: Open or shorted bus wiring to the battery energy control module, Corroded or loose connector / poor ground, Blown fuse / lost low-voltage power feed, Low 12V battery voltage, Failed battery energy control module. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix U0111 on a Mercedes-Benz?▼
Repair costs vary widely depending on the root cause and specific Mercedes-Benz model.
Which Mercedes-Benz models have U0111 documented?▼
Au7o has documented U0111 on 4 Mercedes-Benz models: EQE, EQS, EQS SUV, GLB.