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Mercedes-Benz B161609

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 tur

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceService evaluation is appropriate because the documented condition can make 12 V output regulation unstable or switch off, and Mercedes-Benz specifies XENTRY Diagnosis for the DC/DC converter check.
Confidence95%

Quick answer

B161609 is documented by Mercedes-Benz as a DC/DC converter fault in which reduced resistance at the high-voltage (HV) voltage divider causes incorrect HV-voltage measurement. The 12 V output regulation may become unstable or switch off. Mercedes-Benz’s documented remedy is to check the DC/DC converter with XENTRY Diagnosis.

This page separates verified manufacturer/regulator evidence from supporting material. Unsupported causes, repairs or safety conclusions are not guessed.

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1. What does B161609 mean?

B161609 is documented by Mercedes-Benz as a DC/DC converter fault in which reduced resistance at the high-voltage (HV) voltage divider causes incorrect HV-voltage measurement. The 12 V output regulation may become unstable or switch off. Mercedes-Benz’s documented remedy is to check the DC/DC converter with XENTRY Diagnosis.

2. Technical explanation

According to Mercedes-Benz communication LI54.10-P-079534, reduced resistance at the HV voltage divider can cause the DC/DC converter to measure HV voltage incorrectly. This can make regulation of the vehicle’s 12 V output voltage unstable or cause it to turn off. The communication also states that the DC/DC converter may provide no output voltage or output current.

3. What system is affected?

DC/DC converter, including its HV voltage-divider measurement and 12 V output-voltage regulation.

4. How serious is this code?

Not yet established by verified evidence.

5. Symptoms you may notice

  • A red 12 V battery warning message in the instrument cluster.
  • The DC/DC converter may provide no output voltage or output current.
  • The 12 V output-voltage regulation may be unstable or may turn off.

6. Possible causes

  • Reduced resistance at the HV voltage divider, causing incorrect HV-voltage measurement by the DC/DC converter.

7. Can I still drive the vehicle?

Not yet established by verified evidence.

8. Can I charge the vehicle?

Not yet established by verified evidence.

9. What you can safely do

  • Arrange diagnosis by a qualified Mercedes-Benz service provider using XENTRY Diagnosis.
  • Do not attempt high-voltage component testing or repair yourself.

10. Step-by-step troubleshooting

  1. Mercedes-Benz specifies checking the DC/DC converter using XENTRY Diagnosis.
  2. The cited communication notes that B161609 may be stored in the EZS or may be current, while no DTC may be present in the DC/DC converter.

11. When to contact service

Service evaluation is appropriate because the documented condition can make 12 V output regulation unstable or switch off, and Mercedes-Benz specifies XENTRY Diagnosis for the DC/DC converter check.

12. What the service center may check

  • Check the DC/DC converter with XENTRY Diagnosis.
  • Assess whether B161609 is stored in the EZS or is current.
  • Evaluate DC/DC converter output voltage and output current as part of the diagnostic process.

13. Possible repair or resolution

  • Not yet established by verified evidence. The supplied Mercedes-Benz communication specifies diagnosis of the DC/DC converter with XENTRY Diagnosis but does not provide a verified repair procedure in the available evidence.

14. Affected vehicles

15. Related TSBs / service bulletins

  • Mercedes-Benz LI54.10-P-079534, referenced by NHTSA Manufacturer Communication 11021802, published August 8, 2025. It documents B161609, a red 12 V battery warning message, possible loss of DC/DC output voltage or current, the HV voltage-divider resistance cause, and XENTRY Diagnosis as the stated remedy.

16. Recall information

  • Not yet established by verified evidence.

17. Official manufacturer information

Verified official source: NHTSA Manufacturer Communication 11021802, Mercedes-Benz LI54.10-P-079534: https://static.nhtsa.gov/odi/ffdd/tsbs/TSBS_RECEIVED_2025-2026.zip#nhtsa_id=11021802

19. Frequently asked questions

What does Mercedes-Benz DTC B161609 mean?

It indicates that reduced resistance at the HV voltage divider causes the DC/DC converter to measure HV voltage incorrectly. Mercedes-Benz states that 12 V output-voltage regulation can then become unstable or turn off.

Which vehicles are covered by the supplied applicability evidence?

The verified applicability evidence identifies U.S.-market Mercedes-Benz EQS vehicles for model years 2022 through 2025.

Can B161609 cause a 12 V battery warning?

Yes. The cited Mercedes-Benz communication lists a red 12 V battery warning message in the instrument cluster as the complaint.

Is the DC/DC converter guaranteed to store its own DTC?

No. The communication states that B161609 may be stored in the EZS or be current, with no DTC in the DC/DC converter.

What is the documented diagnostic action?

Mercedes-Benz specifies a check of the DC/DC converter using XENTRY Diagnosis.

20. Sources & verification

Verified
Mercedes-Benz B161609: Due to a reduction in resistance at the HV… | EV Diagnostics