2023 Mercedes-Benz EQB 350 4MATIC

Mercedes EQB U0100 BMS Communication Loss — Gateway Module Software Conflict

U0100 U0415 B100100 Published 2025-04-28 Updated 2025-04-28
Mercedes EQB U0100 BMS gateway software communication CAN

2023 Mercedes EQB 350 4MATIC presented with U0100 BMS communication loss and inability to start one day after visiting a Mercedes dealer for an unrelated recall. Root cause: partial gateway module (STAR Diagnosis) software update installed during recall service had left a CAN routing table conflict.

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The Problem
2023 Mercedes-Benz EQB 350 4MATIC (21,300 miles) presented with 'EV System Fault' and U0100 the morning after a scheduled recall service at a Mercedes dealer. U0100 (Lost Communication with BMS), U0415 (Invalid Data from BMS), and B100100 (Central Gateway Internal Fault) stored.
Diagnostic Procedure
  1. 1. Confirm U0100, U0415, and B100100. All codes appeared simultaneously after dealer visit — points to a software-related event.
  2. 2. Request dealer service record. Recall N202312 (seatbelt pre-tensioner software) was performed. As part of the process, CGEWAY module (Central Gateway) received a partial software update via STAR Diagnosis.
  3. 3. Check CGEWAY software version. Current: 0062.011. Available: 0062.013. The recall service installed 0062.011 but did not complete the recommended full CGEWAY update to 0062.013.
  4. 4. The incomplete update left the CAN routing table in a hybrid state — new routing entries conflicting with old ones, causing BMS to drop off the network.
  5. 5. Perform complete CGEWAY software update to 0062.013 via STAR Diagnosis with stable power supply.
  6. 6. After update: clear all codes. BMS visible on CAN network. Vehicle enters Ready state.
  7. 7. Full charge and drive cycle. All systems normal. No fault return.
Resolution & Root Cause
CGEWAY module updated to version 0062.013. BMS communication restored. All codes cleared.
💡 Key Lesson
U0100 BMS communication loss appearing the day after dealer service on Mercedes EQB — always review what software operations were performed. Partial CGEWAY updates during recall service are a known source of CAN routing conflicts. The fix is completing the interrupted software update, not module replacement. Always confirm target software version versus installed version in STAR Diagnosis.
About This Case

This case was solved remotely by an HVDesk specialist with 15+ years of hands-on experience across major EV platforms including Tesla, Hyundai/Kia, Volkswagen ID series, BMW i-series, and Ford EVs. The procedure was provided as structured remote support to an independent auto repair shop.