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Viessmann Error Codes & Diagnostic Codes

Updated · by Aurora Star Tech Inc.

Viessmann error codes and diagnostic codes: look up a code to see what it means, the likely causes and the steps to fix it.

Viessmann error codes by equipment type

Viessmann Boiler error codes

CodeMeaning
A.12Real-time clock battery flat
A.18Possible condensate back-up in heat cell
A.19Temperature limiter has responded
A.20Service interval could not be activated
Connection errorDisplay link lost to HMU
F.5Sensor circuit fault at plug 33 (X6)
F.7DHW storage tank sensor open circuit
F.8DHW storage tank sensor short circuit
F.11Solar collector sensor open circuit
F.12Solar collector sensor short circuit
F.13Outside temperature sensor open circuit
F.14Outside temperature sensor short circuit
F.15Storage tank sensor open circuit (solar/backup)
F.16Storage tank sensor short circuit (solar/backup)
F.29Low loss header sensor open circuit
F.30Low loss header sensor short circuit
F.49Flue gas temperature sensor open circuit
F.50Flue gas temperature sensor short circuit
F.57Room temperature sensor open circuit
F.58Room temperature sensor short circuit
F.59Supply voltage too low, burner locked out
F.62High limit safety cut-out tripped
F.63Flue gas temperature limiter tripped
F.67Ionization current outside permitted range
F.68Flame signal present at burner start
F.69Ionization current outside permitted range (valve/electrode check)
F.70BCU internal error
F.71Fan speed too low
F.72Fan idle state not reached
F.73BCU internal communication error
F.74Water pressure too low, burner locked out
F.77BCU data memory error
F.89Internal circulation pump blocked
F.91DIO module communication error
F.92ADIO module communication error
F.94PlusBus voltage error
F.100PlusBus voltage error
F.104External fault message input active
F.142CAN bus communication error
F.143Fan overheating (air mass flow sensor / recirculation)
F.160CAN bus communication error (external/internal)
F.161BCU data memory access error
F.163BCU memory checksum error
F.180Gas pressure too low
F.182Outlet temperature sensor short circuit
F.183Outlet temperature sensor open circuit
F.184Supply temperature sensor / high limit short circuit
F.185Supply temperature sensor / high limit open circuit
F.299Time and date incorrect
F.342BCU communication error
F.345Temperature limiter tripped, auto restart after cooling
F.346Ionization current calibration error
F.348Gas modulation valve fault
F.349Air mass flow not detected correctly
F.350Ionization current outside permitted range (BCU)
F.351Ionization current outside permitted range (BCU)
F.352CO limit inside appliance exceeded
F.353Insufficient gas supply, output reduced
F.354Gas modulation valve tolerance outside range
F.355Analogue signal reference check: flame signal at start
F.357Insufficient gas supply
F.359No ignition spark
F.361No or weak flame signal at burner start
F.366Gas valve supply does not switch off
F.367Gas valve supply does not switch off
F.369Flame loss right after ignition (safety time)
F.370Fuel or modulation valve will not close
F.372Repeated flame loss during calibration
F.373Heat transfer too low during calibration
F.377Ionization post-adjustment conditions not met
F.378Flame loss during stabilization or operation
F.379Flame signal missing or insufficient
F.380Flame loss right after ignition (safety time)
F.381Flame loss during operation
F.382Error counter limit exceeded
F.383Possible gas line contamination
F.384Possible gas line contamination
F.385Short circuit on ionization signal 1
F.386BCU faulty
F.387Ionization current ground fault
F.388BCU faulty
F.395IO electrode ground fault
F.396BCU faulty
F.399IO electrode ground fault
F.400BCU faulty
F.401IO electrode ground fault
F.402BCU faulty
F.403IO electrode ground fault
F.404BCU faulty
F.405IO electrode ground fault
F.406BCU faulty
F.408BCU faulty
F.410BCU faulty
F.416Flue gas temperature sensor mispositioned
F.417BCU faulty
F.418BCU faulty
F.425Time synchronization failed
F.430Gateway communication error
F.446Supply sensor / high limit deviation
F.447Ionization current signal deviation
F.448Ionization current signal deviation
F.449Program run monitoring error
F.450Program run monitoring error
F.451Program run monitoring error
F.452Program run monitoring error
F.453Sequence synchronization error
F.454Wrong BCU software version
F.455Program run monitoring error
F.456Program run monitoring error
F.457Fan sluggish or blocked
F.458Reset sequence fault
F.463Contaminated combustion air / flue recirculation
F.464Ionization current too low during calibration
F.467Gas supply insufficient during calibration
F.468Ionization current too high during calibration
F.471Sensor circuit fault (call for heat)
F.473HMU communication error
F.474Program run monitoring error
F.477Solar differential temperature monitoring
F.517Remote control not working
F.527Wrong HMU parameter set
F.528Wrong BCU parameter set
F.530Solar sensor missing or open
F.538System return sensor open (SDIO)
F.540Condensate back-up in heat cell
F.544HC2 mixed supply sensor open circuit
F.545HC2 mixed supply sensor short circuit
F.546HC3 mixed supply sensor open circuit
F.547HC3 mixed supply sensor short circuit
F.548HC4 mixed supply sensor fault (open circuit)
F.549HC4 mixed supply sensor short circuit
F.574HC1 room sensor not available
F.666DHW preheating sensor TS3 open circuit
F.667DHW preheating sensor TS3 short circuit
F.668DHW reheating sensor TS4 open circuit
F.669DHW reheating sensor TS4 short circuit
F.670Buffer sensor TS3 open circuit
F.671Buffer sensor TS3 short circuit
F.672Thermostat-function sensor TS3 open circuit
F.673Thermostat-function sensor TS3 short circuit
F.691No combustion air supply feedback
F.762System pressure too low
F.763Gas pressure too high
F.764Lag boiler reports a fault
F.765Lead boiler communication error
I.56External demand active
I.57External blocking active
I.59Parameters restored
P.1Service interval reached
P.4Top up heating water
P.8Service due after burner hours
S.60Summer mode active
S.74Heating suppression
S.75DHW recirculation pump active
S.94No demand, external hook-up HC1
S.95No demand, external hook-up HC2
S.96No demand, external hook-up HC3
S.154Internal flow switch open

Viessmann Mini-Split error codes

CodeMeaning
--Indoor units mode conflict
APWi-Fi pairing (AP mode)
CLFilter cleaning reminder / Active Clean
CPRemote switched off
d1Demand response signal DR1 received
d2Demand response signal DR2 received
d3Demand response signal DR3 received
dEDemand response input error
dFDefrost
E-C-OECO mode
E1Indoor / outdoor communication error
EC07Outdoor fan speed out of range
EC50Outdoor temperature sensor fault
EC51Outdoor EEPROM error
EC52Condenser coil sensor (T3) fault
EC53Outdoor ambient sensor (T4) fault
EC54Discharge temperature sensor (TP/T5) fault
EC55IPM temperature sensor fault
EC56Indoor coil outlet sensor (T2B) fault
EC57Refrigerant pipe sensor fault
EC71Outdoor fan motor over-current
EC72Outdoor fan motor phase loss
EH0AIndoor EEPROM error
EH0bIndoor PCB to display board communication error
EH00Indoor EEPROM error
EH02Zero-crossing signal error
EH03Indoor fan speed out of range
EH30Indoor external fan low voltage
EH31Indoor external fan over voltage
Eh60Room sensor (T1) fault
Eh61Indoor coil sensor (T2) fault
EL0CRefrigerant leak detected
EL01Indoor / outdoor communication error
F0Current overload protection
F1Outdoor ambient sensor (T4) fault
F2Condenser coil sensor (T3) fault
F3Discharge sensor (T5) fault
F4Outdoor EEPROM error
F5Outdoor fan speed out of control
FbVapor injection inlet sensor fault
FCForced cooling
FdVapor injection outlet sensor fault
FH 0dFault - see outdoor unit
FH 0PAP mode on / no Wi-Fi kit
FL14Indoor and outdoor units not compatible
FPLow-temperature heating (8 C mode)
J0Outdoor coil overheat in cooling
J1Indoor coil temperature protection in heating
J2Discharge temperature protection
J3PFC module protection
J4Main board to IPM board communication error
J5High pressure protection
J6Low pressure protection
J8AC voltage protection
LC01Speed limited by condenser temperature
LC02Speed limited by discharge temperature
LC03Speed limited by current
LC05Speed limited by voltage
LC06IPM high temperature / PFC frequency limit
LH00Speed limited by indoor coil temperature
LH07Speed limited by remote
LLControls locked
nANo fault
nFFilter replacement reminder
ODU --Outdoor board standby
ODU 00Wiring / piping check finished
ODU CEAutomatic wiring / piping check running
ODU E0Outdoor EEPROM error (outdoor board)
ODU E2Indoor / outdoor communication error (outdoor board)
ODU E3IPM to main board communication error (outdoor board)
ODU E4Outdoor or T2B sensor fault (outdoor board)
ODU E5Over or under voltage (outdoor board)
ODU E6PFC module protection (outdoor board)
ODU E8Outdoor fan speed fault (outdoor board)
ODU EdAdapter / inverter board to main board communication error
ODU F1Zone A coil outlet sensor (T2B-A) fault
ODU F2Zone B coil outlet sensor (T2B-B) fault
ODU F3Zone C coil outlet sensor (T2B-C) fault
ODU F4Zone D coil outlet sensor (T2B-D) fault
ODU F5Zone E coil outlet sensor (T2B-E) fault
ODU F6Zone F coil outlet sensor (T2B-F) fault
ODU Hz readoutCompressor running frequency
ODU LCLow ambient cooling mode
ODU LPLow outdoor temperature protection (outdoor board)
ODU P0Compressor top overheat (outdoor board)
ODU P1High pressure protection (outdoor board)
ODU P2Low pressure protection (outdoor board)
ODU P3Current overload (outdoor board)
ODU P4Discharge temperature protection (outdoor board)
ODU P5Condenser high temperature (outdoor board)
ODU P6Inverter module (IPM) fault (outdoor board)
ODU PHCompressor pre-heat
ODU ROOil return cycle
OffTimer off
OnTimer on
P0Inverter module (IPM) fault
P1Over or under voltage protection
P2Compressor top overheat (OLP)
P3Low outdoor temperature cut-off in heating
P4Compressor drive fault
P7IPM temperature sensor fault
PC0ACondenser high temperature protection
PC0FPFC module protection
PC0LOutdoor temperature too low
PC00Inverter module (IPM) protection
PC02Compressor top overheat (OLP)
PC03Pressure protection
PC04Inverter compressor drive error
PC06Discharge temperature protection
PC08Outdoor over-current protection
PC10Low AC supply voltage
PC11AC supply voltage protection (over voltage)
PC12DC bus high voltage / 341 MCE error
PC30High pressure protection
PC31Low pressure protection
PC40Main chip to compressor drive chip communication error
PC41Current input detection protection
PC42Compressor start failure
PC43Compressor phase loss
PC44Zero speed protection
PC45Compressor drive chip (IR / 341 PWM) failure
PC46Compressor speed out of control
PC49Compressor over-current
PCA1Refrigerant pipe condensation protection
PH09Anti-cold-air in heating
PH90Evaporator coil too hot
PH91Evaporator coil too cold
SCSelf clean running
SDPower abnormal detection

Find codes by Viessmann model

Vitodens 200-W B2HE

B2HE-85B2HE-120B2HE-150B2HE-199

Viessmann Vitocal 200-S DLCM(R/H)B multi-zone outdoor

DLCMHBH24CAKDLCMHBH30DAKDLCMHBH36DAKDLCMHBH48EAKDLCMRBH18BAKDLCMRBH36DAKDLCMRBH48EAK

Viessmann DLFSHB high wall indoor

DLFSHBH09XAKDLFSHBH12XAJDLFSHBH12XAKDLFSHBH18XAKDLFSHBH24XAK

General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.

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