Mercedes-Benz AMG C43 2021–2026 — technical service bulletin

Bulletin LI54.10-P-080199 · NHTSA communication 11027656 · issued Jan 14, 2026

Technical service bulletin

communication type

Electrical System

component

2021–2026

model years

vehicle entries

Official summary

Complaint For the potentially affected vehicles, excessively high aging of the battery was calculated at cold battery temperatures (<10°C) and the MIL activated accordingly, even though there is no corresponding high level of aging physically. In this regard, the fault code P0A7F00 "The age limit of the hybrid/high-voltage battery module has been reached" is displayed in the N127 PTCU control unit and/or A66 battery module control unit (48 V battery). Cause Faulty computation of the age limit of the 48 V battery. Remedy Step 1: Software update of A66 battery module (48 V battery) Step 2: Perfo

Vehicles covered

What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.