Viessmann Vitocal fault codes

What each code means, from Viessmann Vitocal's own service literature, and which UK models it applies to.

Viessmann Vitocal heat pumps

F.1Lead break, flow temp secondary/HC1 F.2Short circuit, flow temp secondary/HC1 F.3Lead break, secondary return temp F.4Short circuit, secondary return temp F.7Lead break, cylinder temp F.8Short circuit, cylinder temp F.13Lead break, outside temp (0°C substitute used)F.14Short circuit, outside temp (0°C substitute used)F.33Lead break, air-inlet temp F.34Short circuit, air-inlet temp F.74Hydraulic system pressure too low F.75No flow in secondary circuit or flow sensor faulty F.87Indoor safety valve opened, system pressure too high F.91DIO electronics-module comms error F.92ADIO electronics-module comms error F.93M2IO electronics-module comms error6 models F.94SDIO electronics-module comms error6 models F.99PlusBus comms error (modules unavailable)6 models F.100PlusBus short circuit F.101PlusBus voltage error F.102WiFi comms-module error F.103HMI programming-unit comms error6 models F.104External fault-message input active (EM-EA1/DIO)6 models F.111Lead break, liquid-gas temp heating F.112Short circuit, liquid-gas temp heating F.117Lead break, evaporator suction-gas temp F.118Short circuit, evaporator suction-gas temp F.123Lead break, liquid-gas temp condenser F.124Short circuit, liquid-gas temp condenser F.147Lead break, compressor suction-gas temp F.148Short circuit, compressor suction-gas temp F.149Lead break, liquid-gas temp cooling (runs on substitute)F.150Short circuit, liquid-gas temp cooling (runs on substitute)F.151Lead break, hot-gas temp F.152Short circuit, hot-gas temp F.155Fault, electronic expansion valve 16 models F.156Fault, electronic expansion valve 26 models F.160CAN-bus general comms fault between modules6 models F.425Time sync not possible F.430Gateway comms error F.431KNX/TP gateway comms error F.454Wrong operating-software version across modules (HPMU/EHCU/VCMU)F.472Energy-meter comms error F.519BACnet/IP gateway comms error F.520Modbus comms error inverter↔VCMU6 models F.542Lead break, flow temp HC1 with mixer (or wrong commissioning)6 models F.543Short circuit, flow temp HC1 with mixer6 models F.544Lead break, flow temp HC2 with mixer F.545Short circuit, flow temp HC2 with mixer F.546Lead break, flow temp HC3 with mixer F.547Short circuit, flow temp HC3 with mixer F.548Lead break, flow temp HC4 with mixer F.549Short circuit, flow temp HC4 with mixer F.623Lead break, return temp (mixer HC1)6 models F.624Short circuit, return temp (mixer HC1)6 models F.625Lead break, return temp HC26 models F.626Short circuit, return temp HC26 models F.627Lead break, return temp HC36 models F.628Short circuit, return temp HC36 models F.629Lead break, return temp HC46 models F.630Short circuit, return temp HC46 models F.685HPMU electronics-module comms error (frost protection enabled)6 models F.686VCMU refrigerant-circuit-controller comms error F.687EHCU electronics-module comms error F.770Lead break, flow temp secondary downstream of condenser F.771Short circuit, flow temp secondary downstream of condenser F.772Lead break, oil-sump temp F.773Short circuit, oil-sump temp F.788Fault, control/supply of 4/3-way valve F.7904/3-way valve motor mis-mounted or valve faulty F.791Phase L1 missing on instantaneous heating water heater F.792Phase L2 missing on instantaneous heating water heater F.793Phase L3 missing on instantaneous heating water heater F.797Secondary/HC1 pump faulty F.798HC2 pump faulty F.799Secondary/HC1 pump faulty F.800HC2 pump faulty F.8014-way diverter valve faulty, no circuit reversal F.808Lower fan not running F.812Upper fan not running F.819Lead break, EEV16 models F.820Lead break, EEV26 models F.823Short circuit, EEV16 models F.824Short circuit, EEV26 models F.827High-limit safety cut-out responded on instantaneous heater6 models F.829Flow too low — outdoor-unit ball-valve filter contaminated6 models F.830Power supply on inverter faulty F.831Power supply on inverter faulty F.832Inverter temperature sensor faulty F.833Inverter temperature sensor faulty F.834Power supply on inverter faulty F.835Unsuitable / mis-programmed inverter F.836Overvoltage fault on inverter F.837Power supply on compressor faulty F.838Inverter control faulty6 models F.839Compressor blocked6 models F.841Compressor running unevenly (excess torque / high power draw)F.843Overvoltage shutdown, inverter F.845Unsuitable / mis-programmed inverter F.846Compressor rotating field counter-rotating F.847Voltage error on inverter F.848Voltage error on inverter F.864Defrost attempt unsuccessful F.865High-pressure fault (air / shut circuit / blocked pumps / dirty condenser / faulty HP sensor / setpoints too high)F.866Low-pressure fault (low refrigerant / dirty evaporator / fans blocked or faulty)F.867Float air-vent valve responded — air in circuit / faulty air-vent / refrigerant in float valve6 models F.876Lead break, flow sensor F.881Refrigerant-circuit safety shutdown F.912Interior temp sensor fault F.913Interior (inverter) temperature too high6 models F.983Internal inverter fault F.984Control of EEV1 faulty F.985Control of EEV2 faulty F.990Short circuit, secondary-circuit temp sensor F.991Lead break, secondary-circuit temp sensor F.992Short circuit, ext. heating-water/coolant buffer sensor F.993Lead break, ext. heating-water/coolant buffer sensor F.994Short circuit, ext. heating-water buffer sensor F.995Lead break, ext. heating-water buffer sensor F.996Short circuit, ext. coolant buffer sensor F.997Lead break, ext. coolant buffer sensor F.998Flow-rate signal faulty / CAN-bus F.1009Oil-sump heater fault F.1010Secondary-circuit pressure sensor fault F.1011High-pressure sensor fault F.1012Low-pressure sensor fault F.1045External heat generator not ready F.10493/2-way mixing valve not switching (ext. heat gen.)F.1050Short circuit, boiler-water temp ext. heat generator F.1051Lead break, boiler-water temp ext. heat generator F.1054Max temp of external heat generator exceeded F.1056Inverter relay faulty A.2frost protection enabled A.11heating only in some rooms A.12incorrect time A.16compressor + heater off A.17no increased DHW hygiene A.21indoor safety valve opened A.62no pump scan HC1 A.63no pump scan HC2 A.65no heating HC2 A.66HC1 pump not running A.68HC2 pump not running A.70flow too low6 models A.71low compressor output A.72low compressor output A.73low compressor output A.74unusual noise/operation A.75unusual noise/operation A.80compressor can't start A.81COP too low / circuit off A.82unstable control A.83no DHW heating A.84no room heating A.85no DHW heating A.86no heating HC1 A.87no heating HC2 A.91circuit off, aux-heater only A.93refrigerant circuit impaired A.94refrigerant circuit impaired A.96unusual noise/operation

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