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Mercedes-Benz P0C3B00

As a consequence, on vehicles with BMS30EB02, the DTC for the auxiliary assembly fuse P0E2F00 can be set. This triggers the yellow HV drive system warning message. In the ignition

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceContact an authorized Mercedes-Benz service provider promptly if P0C3B00 is stored or any red 12 V, HV, or HV drive-system warning is displayed.
Confidence95%

Quick answer

For certain 2022–2025 U.S. Mercedes-Benz EQB and G-Class vehicles covered by LI54.10-P-079533, P0C3B00 may be stored by the DC/DC converter as part of a documented fault-code group. The bulletin describes 12 V, HV, and instrument-cluster warning messages that can progress if initial warnings are ignored during the same ignition cycle. The exact definition of P0C3B00 is not established by the supplied verified evidence.

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 P0C3B00 mean?

For certain 2022–2025 U.S. Mercedes-Benz EQB and G-Class vehicles covered by LI54.10-P-079533, P0C3B00 may be stored by the DC/DC converter as part of a documented fault-code group. The bulletin describes 12 V, HV, and instrument-cluster warning messages that can progress if initial warnings are ignored during the same ignition cycle. The exact definition of P0C3B00 is not established by the supplied verified evidence.

2. Technical explanation

Mercedes-Benz bulletin LI54.10-P-079533 documents P0C3B00 in the DC/DC converter. It may occur in a group with P0E9700, P0E5400, and P0C4000. The bulletin also identifies a second group—P1D0B00, P1CA000, and U011500—and states that not all DTCs in a group are necessarily triggered. In vehicles with BMS30EB02, P0E2F00 for the auxiliary assembly fuse can also be set; the bulletin states that this triggers the yellow HV drive-system warning. The supplied evidence does not establish that P0C3B00 itself directly sets that warning.

3. What system is affected?

DC/DC converter. The supplied evidence also references the 12 V system, HV warning messages, the instrument cluster, BMS30EB02, and the auxiliary assembly fuse.

4. How serious is this code?

Not yet established by verified evidence. The official bulletin does document possible red 12 V battery, white HV, red HV, and yellow HV drive-system warnings.

5. Symptoms you may notice

  • A red 12 V battery message may be displayed.
  • A white HV warning message may be displayed.
  • A warning message may be displayed in the instrument cluster.
  • If initial warning messages are ignored in the same ignition cycle, additional warnings may be displayed, including a red HV warning and a yellow HV drive-system warning.

6. Possible causes

  • The root cause of P0C3B00 is not yet established by verified evidence.
  • For vehicles with BMS30EB02, the bulletin states that P0E2F00 for the auxiliary assembly fuse can be set as a consequence; it does not establish this as the cause of P0C3B00.

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

  • Do not ignore red 12 V, HV, or HV drive-system warning messages.
  • Arrange diagnosis by an authorized Mercedes-Benz service provider.
  • Do not attempt high-voltage system repairs yourself.

10. Step-by-step troubleshooting

  1. Have the DC/DC converter checked for P0C3B00 and the documented accompanying DTCs.
  2. Record any active instrument-cluster and vehicle warning messages for the service visit.
  3. Have a qualified Mercedes-Benz technician determine whether the vehicle is equipped with BMS30EB02 and whether P0E2F00 is present.

11. When to contact service

Contact an authorized Mercedes-Benz service provider promptly if P0C3B00 is stored or any red 12 V, HV, or HV drive-system warning is displayed.

12. What the service center may check

  • Read DC/DC converter fault memory for P0C3B00, P0E9700, P0E5400, and P0C4000.
  • Check for the additional documented DTCs P1D0B00, P1CA000, and U011500.
  • For vehicles with BMS30EB02, check whether P0E2F00 for the auxiliary assembly fuse is stored.
  • Evaluate the vehicle using Mercedes-Benz bulletin LI54.10-P-079533 as applicable.

13. Possible repair or resolution

  • The supplied verified evidence does not provide a repair procedure or confirmed repair resolution.

14. Affected vehicles

15. Related TSBs / service bulletins

  • Mercedes-Benz LI54.10-P-079533, published through NHTSA Manufacturer Communications 11021800 (2025-08-08), 11021970 (2025-08-05), 11023154 (2025-09-16), 11028815 (2026-02-14), and 11029977 (2026-03-11).
  • The supplied bulletin evidence applies to certain U.S. 2022–2025 Mercedes-Benz EQB and G-Class vehicles.

16. Recall information

  • Not yet established by verified evidence.

17. Official manufacturer information

Official source: NHTSA Manufacturer Communication LI54.10-P-079533, available through the supplied NHTSA communication records.

19. Frequently asked questions

What does P0C3B00 mean on a Mercedes-Benz EV?

Its exact definition is not established by the supplied verified evidence. The official bulletin identifies it as a DC/DC converter DTC in a documented fault-code group.

Which other codes may occur with P0C3B00?

The bulletin lists P0E9700, P0E5400, and P0C4000 in the same group. It also lists P1D0B00, P1CA000, and U011500 as another group that may be stored. Not all listed codes are necessarily triggered.

Does P0C3B00 mean it is unsafe to drive or charge?

Not yet established by verified evidence.

What warning messages can be associated with this bulletin?

The bulletin documents red 12 V battery, white HV, red HV, and yellow HV drive-system warnings, with additional warnings potentially shown if initial warnings are ignored in the same ignition cycle.

20. Sources & verification

Verified
Mercedes-Benz P0C3B00: As a consequence, on vehicles with BMS30EB02,… | EV Diagnostics