WenmarOpen by Wenmar Pro

Service bulletin LI54.21-P-078926

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

The communication, as NHTSA indexes it (as of 2026-10-19)
TypeService bulletin
NHTSA id11021897
Published by NHTSA2025-08-15
Manufacturer's numberLI54.21-P-078926
Manufacturer's date2025-08-04
NHTSA componentENGINE

NHTSA's summary

Complaint: Check engine light comes on when driving/starting the vehicle. No drivability concerns. Cause: Communication error in G1/3 - 48 V on-board electrical system battery (48 V LIB) or N127 - 'Drivetrain' control unit (PTCU)saved and/or current Remedy: Update the software for the control unit G1/3 - 48 V on-board electrical system battery (48 V LIB) : --> Remedy-SW A001902042425/12 If the fault profile still occurs with the installed software, check the wiring and the plug contacts: UG1/3 - 48 V on-board electrical system battery (48 V LIB) N83/1 - DC/DC converter (DDW) N127 - 'Drivetrain' (PTCU) control unit NOTE: Replacing parts does not remedy the problem.

The document

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Engine

Vehicles listed
MERCEDES-BENZ AMG CLA352020 to 2024
MERCEDES-BENZ AMG CLA452020 to 2024
MERCEDES-BENZ AMG GLA452021 to 2023
MERCEDES-BENZ AMG GLB352021 to 2025
MERCEDES-BENZ CLA 2502020 to 2025
MERCEDES-BENZ GLA 2502021 to 2025
MERCEDES-BENZ GLA 250 4MATIC2024
MERCEDES-BENZ GLB 2502020 to 2025

Listing a model year does not mean every vehicle of it is concerned: the document says which.