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

Bulletin LI54.10-P-080602 · NHTSA communication 11032890 · issued May 20, 2026

Technical service bulletin

communication type

Electrical System

component

2021–2026

model years

vehicle entries

Official summary

Complaint 48V battery (A66) part numbers A 000 982 78 24, A 000 982 57 30, A 000 982 88 31, A 000 982 50 32, A 000 982 87 32) may trigger a fault message ("48 V Service Required" with fault codes P0ADA91, P0ADE91, P0AA100, P0ADD00 or P0AA000) in the instrument cluster. This fault message may prevent the 48 V battery contactors from opening automatically if the 12 V power supply is interrupted. In this case, the 48 V on-board electrical system, including connected components, remain energized. Cause The contactors of the 48 V battery do not open, resulting in residual voltage (> 3V) even when t

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.