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All De Dietrich error codes

This page brings together De Dietrich error codes sorted by type of failure: what each code means, its likely causes, and what you can safely check before calling a professional.

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The De Dietrich codes on this page, grouped by type of failure.

general fault

A02.18 A02.55 B00 B02 B11 B14 B17 D05 D07 D14 D15 D17 D20 D27 D32 D37 D38 D99 E00.00 E00.01 H. 02.00 H00.49 H02.25 M04

water flow

A.02.22 B39 B55 L33

domestic hot water

B13 D09

circuit pressure

A.02.06

General fault — De Dietrich

These codes don’t point to a specific part: the unit is signaling that an internal safety feature has tripped.

Code A02.18Informationair-to-water

OBD error

Models concerned: Alezio S V200

Code A02.55Informationair-to-water

Invalid serial number

Models concerned: Alezio S V200

Code B00Informationair-to-water

BL.PSU ERROR

What you can check

Parameter error on the PSU circuit board. Reset the generator type in the #CONFIGURATION menu (refer to the original nameplate)

Models concerned: HPI Evolution

Code B02Informationair-to-water

BL.S.DEPART

What you can check

Faulty connection
Check the wiring between the PCU circuit board and the sensor
Check that the SU circuit board is properly installed
Check that the sensor was mounted correctly
Check the sensor’s resistance

Models concerned: HPI Evolution

Code B11Informationair-to-water

BL.COM SCU

What you can check

Contact the professional who services the unit

Models concerned: HPI Evolution

This fault requires a qualified technician. Do not open the unit.

Code B14Informationair-to-water

BL.S.EXT

What you can check

Check that the sensor is properly connected to the PCU’s S.EXT input. Check the wiring. Check the sensor’s resistance value
Replace it if necessary

Models concerned: HPI Evolution

Code B17Informationair-to-water

BL.PCU ERROR

What you can check

Parameter error on the PCU circuit board. Contact the professional who services the unit

Models concerned: HPI Evolution

This fault requires a qualified technician. Do not open the unit.

Code D05Informationair-to-water

DEF.S.EXT.

What you can check

Faulty connection. Sensor failure. Contact the professional who services the unit

Models concerned: HPI Evolution

This fault requires a qualified technician. Do not open the unit.

Code D07Informationair-to-water

DEF.S.SYST.

What you can check

Faulty connection. Sensor failure. Contact the professional who services the unit

Models concerned: HPI Evolution

This fault requires a qualified technician. Do not open the unit.

Code D14Informationair-to-water

DEF.COM MC

What you can check

Faulty connection. Check the link and connectors

Models concerned: HPI Evolution

Code D15Informationair-to-water

DEF.S.BAL.TP

What you can check

Faulty connection. Sensor failure. Contact the professional who services the unit

Models concerned: HPI Evolution

This fault requires a qualified technician. Do not open the unit.

Code D17Informationair-to-water

DEF.S.BAL.2

What you can check

Faulty connection. Sensor failure. Contact the professional who services the unit

Models concerned: HPI Evolution

This fault requires a qualified technician. Do not open the unit.

Code D20Informationair-to-water

DEF.COM.SOL.

Affected models: HPI Evolution

Code D27Informationair-to-water

DEF.COM.PCU

Affected models: HPI Evolution

Code D32Informationair-to-water

5 RESET:ON/OFF

Affected models: HPI Evolution

Code D37Informationair-to-water

TA-S COURT-CIR

Affected models: HPI Evolution

Code D38Informationair-to-water

TA-S DEBRANCHE

Affected models: HPI Evolution

Code D99Informationair-to-water

DEF.MAUVAIS.PCU

Affected models: HPI Evolution

Code E00.00Informationair-to-water

TDépt ouvert

Affected models: Alezio S V200

Code E00.01Informationair-to-water

Capt TDépt crt-circuité ou temp > plage

Affected models: Alezio S V200

Code H. 02.00Informationair-to-water

Réinit. en cours

Affected models: Alezio AWHP-V200, Alezio S V200

Code H00.49Informationair-to-water

TDépt PAC manquant

Affected models: Alezio S V200

Code H02.25Informationair-to-water

ACI error

Affected models: Alezio S V200

Code M04Informationair-to-water

REVISION

What you can check

The scheduled service date has been reached
Perform maintenance on the heat pump
To clear the service reminder, schedule another date in the #REVISION menu, or set the TYPE REVISION parameter to NON

Affected models: HPI Evolution

Water flow — De Dietrich

Water flow in the heating circuit is insufficient. The usual suspects are the circulator pump, filter, valves, and air in the system.

Code A.02.22Informationair-to-water

ALERTE SYSTÈME DÉBIT

Affected models: Alezio AWHP-V200, Alezio S V200

Code B39Informationair-to-water

BL.DEBIT

What you can check

Check the heat pump’s circulator pump setting. Check that the filter isn’t clogged

Affected models: HPI Evolution

Code B55Informationair-to-water

BL.DEBIT

What you can check

Check the heat pump’s circulator pump setting. Check that the filter isn’t clogged

Affected models: HPI Evolution

Code L33Informationair-to-water

DEF.DEBIT

Affected models: HPI Evolution

Domestic hot water — De Dietrich

There’s a fault in the domestic hot water circuit: tank sensor, three-way valve, or backup heater.

Code B13Informationair-to-water

BL.S.ECS

What you can check

Check that the sensor is properly connected to the S.ECS input on the PCU. Check the wiring. Check the sensor’s resistance (ohm) value
Replace it if necessary

Affected models: HPI Evolution

Code D09Informationair-to-water

DEF.S.ECS

What you can check

Poor connection. Sensor failure. Contact the professional who services the unit

Affected models: HPI Evolution

This fault requires a qualified technician. Do not open the unit.

System pressure — De Dietrich

Code A.02.06Informationair-to-water

WATER PRESSURE ALERT

Models affected: Alezio AWHP-V200, Alezio S V200

All De Dietrich codes published on the site

This list updates automatically whenever a new guide is added.

Technical information provided for general guidance, based on manufacturer documentation and field feedback. It does not replace a diagnosis by a qualified professional. Found an error on this page? Report it.