# 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.

- Type: Service bulletin
- NHTSA id: 11016046
- Published by NHTSA: 2025\-03\-28
- Manufacturer's number: LI54.21\-P\-078926
- Manufacturer's date: 2025\-03\-26
- NHTSA component: ELECTRICAL SYSTEM; ENGINE

## NHTSA's summary

Complaint Check engine light comes on when driving/starting the vehicle. No drivability concerns. Cause SW conflict of the 48V battery Remedy 1.\-Check for SW in the 48V battery. 1. If SW is available, update the 48V battery. 2. Clear all faults and perform a few drive cycles. 3. If no faults return, the vehicle can be released. 2.\-If no SW available, perform the following: \- Charge the batteries \(\<5A charging current\) \- Erase the fault codes \- Access the 12V battery contacts \- Ignition off and bus sleep for 10 minutes \- Disconnect the 12V battery \- Wait 10 minutes \- Disconnect Connector 3 at the 48V battery \- Disconnect Connector 5 at the DCDC converter \- Disconnect the 48V and 12V contacts \(40/41 and 30/31\) at the DCDC converter \- Wait for 10 minutes \- Reconnect everything back in opposite order and perform the ISU of the DCDC \- Conduct a test drive and after check for fault codes U014687 and U044287

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2025/MC-11016046-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2025/MC-11016046-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Electrical system, Engine

## Trouble codes named

U0146, U0442

## Vehicles listed

- 2020 to 2024 MERCEDES\-BENZ AMG CLA35
- 2020 to 2024 MERCEDES\-BENZ AMG CLA45
- 2024 to 2025 MERCEDES\-BENZ AMG GLA 35
- 2024 MERCEDES\-BENZ AMG GLA 45S
- 2021 to 2023 MERCEDES\-BENZ AMG GLA35
- 2021 to 2023 MERCEDES\-BENZ AMG GLA45
- 2020 to 2024 MERCEDES\-BENZ CLA 250
- 2020 to 2025 MERCEDES\-BENZ GLA 250

JSON: [/v1/bulletins/11016046](/v1/bulletins/11016046)

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