# Service bulletin LI54.10\-P\-079534

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: 11021802
- Published by NHTSA: 2025\-08\-12
- Manufacturer's number: LI54.10\-P\-079534
- Manufacturer's date: 2025\-08\-08
- NHTSA component: ELECTRICAL SYSTEM

## NHTSA's summary

Complaint: Red 12 V battery warning message in IC DTC stored in EZS or currently: B161609 No DTC in DC/DC converter DC/DC converter is not providing any output voltage or output current Cause: Due to a reduction in resistance at the HV voltage divider, the DC/DC converter measures an incorrect HV voltage. Regulation of the 12 V output voltage is therefore unstable or turns off. Remedy: Check of the DC/DC converter via XENTRY Diagnosis Actuate BUCK mode for approx. 40 s Normally, the output current will jump up to a high value \(e.g. 100 A\) and then slowly drop to the current specified value \(e.g. 50 A\) and then only change slowly and in small increments \(video in attachment\). In the event of this error cause, the DC/DC converter may react in two possible ways: 1\) Despite displayed BUCK mode, the DC/DC converter does not provide any output voltage or output current \(video in attachment\). 2\) The output voltage and output current may experience significant fluctuations/jumps \(several 1\-10 A\) \(video in attachment\). Perform in XENTRY \-\> DC/DC converter N83/1 \-\> Special procedures \-\> "Evaluation of the HV resistance reduction of the DC/DC converter control unit". The special procedure compares the serial number of the installed DC/DC converter with the list of potentially affected parts. Depending on the result: If the serial number can be found in the list of potentially affected component parts, then replace the DC/DC converter. If the serial number cannot be found in the list of potentially affected parts but the problem described applies, then please open a TIPS case and forward to HQ.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2025/MC-11021802-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2025/MC-11021802-9999.pdf)

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

## Components

Electrical system

## Trouble codes named

B1616

## Vehicles listed

- 2022 to 2024 MERCEDES\-BENZ AMG EQS
- 2022 to 2023 MERCEDES\-BENZ AMG EQS 53
- 2023 to 2024 MERCEDES\-BENZ AMG EQS 53 4MATIC
- 2022 MERCEDES\-BENZ EQS 450
- 2023 to 2024 MERCEDES\-BENZ EQS 450 4MATIC
- 2022 to 2024 MERCEDES\-BENZ EQS 450\+
- 2022 to 2024 MERCEDES\-BENZ EQS 580
- 2022 to 2023 MERCEDES\-BENZ EQS 580 4MATIC
- 2023 to 2025 MERCEDES\-BENZ EQS SUV 450 4MATIC
- 2023 to 2025 MERCEDES\-BENZ EQS SUV 450\+
- 2023 to 2025 MERCEDES\-BENZ EQS SUV 580 4MATIC
- 2023 to 2024 MERCEDES\-BENZ redundant EQS 450
- 2024 to 2025 MERCEDES\-MAYBACH EQS SUV 680 4MATIC

JSON: [/v1/bulletins/11021802](/v1/bulletins/11021802)

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