DCDC223 Sensor fault codes due to faulty wake-up behavior
Topic number

LI54.10-P-079533

Version

4

Function group

54.10 - Battery, power supply, voltage converter

Date

2/13/26

Validity

The DC/DC converter type that is installed in model series 243 and 465 can be affected.

Reason for change

Addition of the model variant for model series 465, general adaptation of the information in the "Topic" tab

Complaint
243: Red 12V battery message, white HV warning message, warning message in the IC and if applicable for vehicles
with BMS30EB02 yellow HV drive system
465: Red 12V battery message, white HV warning message, warning message in the IC
If the initial warning messages are ignored in the same ignition cycle, additional warning messages, e.g. red HV
warning message and yellow HV drive system warning message may be shown.
The DC/DC converter has stored a combination of the following two fault code groups:
1. P0C3B00, P0E9700, P0E5400, P0C4000.
2. P1D0B00, P1CA000, U011500.
In some cases, not all DTCs from one of these groups are triggered.
243: 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 cycle in which the red 12 V fault message is displayed, the DC/DC converter does not support the 12 V
on-board electrical system.
This means the 12 V battery may be discharged in the event of longer use.

Attachments
File

Description

DCDC223 243 Sensor issue gelbe Hybrid Antriebssystem 243 yellow HV drive system warning message - can only
WEM.jpg
be deleted via XENTRY

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Cause
In individual ignition cycles, this may result in faulty wake-up behavior of the DC/DC converter.
The DCDC DTCs and warning messages may appear with a time delay.
When accessing the vehicle, the white (243/465) HV warning message is displayed.
When the HV system is switched on (charging, 12V supports, precon, ignition on), the yellow HV drive system
warning message is displayed on the 243 with BMS30EB02 (see below for details).
When the vehicle is started/PT-ready (displayed in the IC), the red 12V battery warning message is displayed for 243
and 465. - This warning message indicates that the DC/DC was not properly initialized in the current cycle and the
12V on-board electrical system is not being supplied.
Since the BMS on 243 uses the HV voltage value to check the auxiliary assembly fuse, the auxiliary assembly DTC
can (with BMS30EB02) be stored as a consequence and the second (yellow) HV drive system warning message can
be displayed in the IC.

Remedy
243 EB330 (BMS30EB02):
Update the DC/DC converter software to version A0019024327
465:
Perform reset of the DC/DC converter, e.g. through a BUS idle or by clearing the fault memory, to exit the faulty state.
Update the DC/DC converter software to the latest version.
!!! Important note: Problems relating to this topic must be invoiced on the damage code for the DC/DC converter
54720. !!!

Disclaimer
NOTE: The information contained in this document is intended for use by trained, professional technicians with the
knowledge to properly and safely perform diagnosis and repairs on Mercedes-Benz vehicles, using Mercedes-Benz
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approved tools and equipment. It informs service technicians about conditions that could occur in certain vehicles and
provides information that could assist in proper vehicle diagnosis, service, or repair. It does not indicate that a defect
is present in any vehicle referenced in this document nor does it imply warranty coverage. DO NOT assume that a
symptom or condition, or a described cause of a symptom or condition, affects any particular vehicle or groups of vehicles, or that a described repair applies to any particular vehicle or groups of vehicles. There can be multiple causes
resulting in the same or similar symptoms or conditions described in this document, and trained professional service
technicians must use their diagnostic skills to make evaluations on a case-by-case basis. The information contained
in this document does not guarantee warranty coverage nor does it extend the vehicle’s warranty in any way.

Symptoms
Overall vehicle > Power supply > Battery/On-board electrical system > Battery/on-board electrical system display
message > Low voltage Charge battery
Overall vehicle > Power supply > High-voltage on-board electrical system > High-voltage battery > Display message
Power generation > Engine management > Electric drive > Electric machine > Power reduced

Control unit/fault code
Control unit

Fault text

N82/9 - Battery management system (BMS) (BMS30EB02)

P0E2F00 - Electrical fuse B for the high voltage has a
malfunction. _

N83/1 - DC/DC converter (DDW) (DCDC223)

P1D0B00 - The internal power supply has a malfunction.
_
U011500 - Communication with control unit 'Drivetrain'
has a malfunction. _
P1CA000 - Initial startup was not performed. _
P0E5400 - Current sensor A of the DC/DC converter has
a short circuit to positive. _
P0C3B00 - Temperature sensor A of the DC/DC converter has a short circuit to positive. _
P0E9700 - Voltage sensor C of the DC/DC converter has
a malfunction. _
P0C4000 - Temperature sensor B of the DC/DC converter
has a short circuit to positive. _

Operation numbers/damage codes
Op. no.

Operation text

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Time

Damage
code

H

54720

SAHARRY

Note

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