Vaillant boiler error codes

Founded nearly a century and a half ago, in the 1874, the German company Vaillant is one of the largest manufacturers of heating equipment in Europe. All equipment of Vaillant is certified for work all over the world. Its high performance and reliability is confirmed by over 100 years of operational experience in many countries of the world. The table below lists the boiler Vaillant error codes. Refer to it in case of any malfunction of boilers Vaillant.

Vaillant ecoTEC SERIES boiler error codes

S. 0No heat demand
S.1Fan running
S. 2Water pump running
S. 3Ignition sequence
S. 4Burner ignited
S. 5Fan and pump running
S. 6Fan over run
S. 7Pump over run
S. 8Anti cycling mode
S.10Hot water demand
S.11Fan running
S.13Ignition sequence
S.14Burner ignited
S.15Fan and pump running
S.16Fan over run
S.17Pump over run
S.20Warmstart demand
S.21Fan running
S.22Pump running
S.23Ignition sequence
S.24Burner ignited
S.25Fan and water pump running
S.26Fan over run
S.27Pump over run
S.28Anti cycling mode
S.30No heating demand from external controls (clamp 3-4 open)
S.31Central heating thermostat knob turned off or no heat demand by the eBUS control unit
S.32Heat exchanger antifreeze active, as fan speed variation is too high. Appliance is within the waiting time of the operation block function
S.34Antifrost mode active
S.36No heating demand from low voltage controls (clamp 7-8-9)
S.41Water pressure > 2,9 bar
S.42Response from accessory modul or defective condensate pump is blockinq burner operation
S.52Water pressure > 2,9 bar
S.53Appliance is within the waiting period of the operation block function due to water shortage (VL-RL spread too big)
S.54Appliance is within the waiting period of the operation block function due to water shortage (temperature gradient)
S.96Return-sensor check is running, demand (DHW or heatinq) is blocked
S.97Water pressure sensor check is running, demand (DHW or heatinq) is blocked
S.98Flow-/Return-sensor check is running, demand (DHW or heating) is blocked

Vaillant ecoTEC PRO boiler error codes

S.00Heating: No heat demand
S.02Heating mode: Pump pre-run
S.03Heating mode: Ignition
S.04Heating mode: Burner on
S.06Heating mode: Fan overrun
S.07Heating mode: Pump overrun
S.08Heating, remaining anti-cycling time xx mins
S.10Domestic hot water requirement via impeller sensor
S.14DHW mode: Burner on
S.20Hot water requirement
S.22DHW mode: Pump pre-run
S.24DHW mode: Burner on
S.31No heat demand: Summer mode
S.34Heating mode: Frost protection
S.46Comfort protection mode, flame loss at minimum load

Vaillant EcoMax Pro 18/28E boiler error codes

Fault CodePossible Cause
F.1Lack of gas, a fault with the ignition or flue, or you may need to adjust the gas valve or replace a defective electrode lead.
F.4Ignition fault.
F.5The system has suffered a fault due to overheating.
F.6Your flow NTC (temperature sensor) has developed a fault.
F.17Check the polarity of your system
F.21The pump could have failed, over run or there could be an issue with the air lock.

Vaillant Turbomax Plus 824/8E boiler error codes

CodesPossible Cause
F.00 NThe flow NTC (Negative Temperature Coefficient Thermostat) cable is either defective or broken and needs replacing.
F.10Short circuit with the NTC.
F.20 (error solution f20)Your boiler has exceeded the maximum temperature and needs to cool.
(error solution f22)
There is dry fire, low water in the system which is overheating. You may have a defective pump or pump lead.
(error solution f24)
Your pump could be obstructed, at low capacity or there could be trapped air. The pressure of your system could be too low.
(error solution f28)
There is insufficient gas, a defective electrode, ignition lead or electronic ignitor. 
F.29(error solution f29)Your flame or pilot light has gone out. Check your flue duck or gas supply to see if there is a problem. 
F.60Your cable loom which connects your gas valve may have short circuited. You could have a defective gas valve or electronic control system.
F.62Your boiler has exceeded the maximum temperature and needs to cool down.
F.63This is an electronic fault within your system. An error with your EEPROM (electrically erasable programmable read-only memory.)
F.64Your flow or backflow NTC has suffered a short circuit or an electronic fault.
F.65Electronic system temperature too high, potentially due to an external heat source or electrical fault.
F.67Electronic fault in flame system.

Vaillant boiler error codes

F.49eBUS faultShort circuit on the eBUS, eBUS overload or two power supplies with different polarities on the eBUS
F.52Mass flow sensor connection faultMass flow sensor not connected/disconnected, plug not connected or incorrectly connected
F.53Mass flow sensor faultMass flow sensor faulty, filter below venturi filter cap wet or blocked, gas flow pressure too low
F.54Gas pressure fault (in combination with F.28/F.29)No or too little gas supply pressure, gas valve closed
F.56Fault: Mass flow sensor regulationGas valve defective, cable harness to gas valve defective
F.57Fault during comfort safety modeIgnition electrode highly corroded
F.61Fault: Gas valve regulationShort circuit/short to earth in cable harness for the gas valve
Gas valve defective (coils shorted to earth)
Electronic defective
F.62Fault: Gas valve switch-off delayDelayed shutdown of gas valve
Delayed extinguishing of flame signal
Gas valve leaking Electronics defective
F.63EEPROM errorElectronics defective
F.64Electronics/NTC faultSupply or return NTC short circuited, electronics defective
F.65Electronic temperature faultElectronics overheating due to external influences, electronics defective
F.67Electronics/flame faultImplausible flame signal, electronics defective
F.68Unstable flame signal faultAir in gas, gas flow pressure too low, wrong air ratio, condensate route blocked, wrong gas restrictor, ionisation flow interruption (cables, electrodes), flue gas recirculation, condensate route
F.70Invalid device specific number (DSN)Spare part case: Display and PCB replaced at same time and DSN not set, wrong or missing output range coding resistor
F.71Flow NTC faultFlow temperature sensor signalling constant value:
Flow temperature sensor incorrectly positioned at supply pipe
Flow temperature sensor defective
F.72Flow/return NTC faultFlow/return NTC temperature difference too great → flow and/or return temperature sensor defective
F.73Water pressure sensor signal in the wrong range (too low)Interruption/short circuit of water pressure sensor, interruption/short circuit to GND in supply line to water pressure sensor or water pressure sensor defective
F.74Water pressure sensor signal outside correct range (too low)Cable to water pressure sensor has short-circuitedd at 5V/24 V or internal fault in water pressure sensor
(error f75)
Fault, no pressure change detection when starting pumpWater pressure sensor and/or pump defective, air in heating installation, too low water pressure in boiler; check adjustable bypass, connect external expansion vessel to return
F.76Overheating protection on primary heat exchanger has respondedCable or cable connections for safety fuse in primary heat exchanger or primary heat exchanger defective
F.77Flue non-return flap/condensate pump faultNo response from flue non-return flap or condensate pump defective
F.78Interruption to DHW outlet sensor at external controllerUK link box is connected, but hot water NTC not bridged
F.83Flow and/or return temperature sesnsor temperature change faultWhen the burner starts, the temperature change registered at flow and/or return temperature sensor is non-existant or too small.
Not enough water in the boiler
Flow and/or return temperature sensor not in correct position at pipe
F.84Fault: Flow/return temperature sensor difference implausibleFlow and return temperature sensors return implausible values
Flow and return temperature sensors have been inverted
Flow and return temperature sensors have not been correctly fitted
F.85Fault: Flow and return temperature sensors incorrectly fittedFlow and/or return temperature sensors have been fitted to the same pipe/wrong pipe
F.92Coding resistor faultThe coding resistor on the PCB does not match the entered gas family. Check the resistor, repeat the gas family check and enter the correct gas family.
F.93Gas group faultCombustion quality outside the permitted range: Wrong gas restrictor, recirculation, wrong gas family, internal pressure measuring point in venturi blocked (do not use lubricant on O-ring in venturi.). Gas family check prematurely terminated.
Communication faultNo communication with PCB

Vaillant ecoMAX pro 18E boiler error codes

F1Ignition fault (lockout) Failed to lightNo gas; Insufficient gas; Incorrect gas valve adjustment; Electrode defect; Ignition lead defect; Electronic igniter defective; Check air inlet duct; Check connections to igniter unit
F4Ignition fault (lockout) Went out when litAs above
F5Overheat faultOverheat stat operated; Maximum temperature exceeded;
Check thermistor connections; Air in system with thermistor at maximum setting; Faulty overheat stat connection; Check that pump is wired into appliance and not from programmer. This would cause no pump overrun
F6Central heating flow NTC faultFlow NTC cable defective/broken NTC faulty
Flow thermistor not fitted correctly, Check pipe work configuration
F10Central heating return NTC faultReturn NTC cable defective/broken NTC faulty Check that thermistor attached correctly to pipe.
F11No reception by main boardConnection fault between main PCB and interface; Faulty interface; Faulty main PCB (processor), Check fan
F12No reception by the local user interfaceAs F.11
F13Main board faultAs F.11
F14Central heating flow t? > 95? CSystem fault; Possible external pump failure; Check NTC on flow Check that pump is wired into appliance and not from programmer. This would cause no pump overrun
F16Flame detection fault
(flame presence >5 s after burner stop)
Gas valve defective
F17Power supply <170 VCheck electrical supply / polarity, Check fan
F18Local user interface faultConnections; Faulty interface
F19Central heating NTC unpluggedCheck NTC connection
F20 (error solution f20)MMI software incompatible with IRIS softwarePossible connection fault
(error solution f24)
Central heating return t? >90?CSystem fault; Possible external pump failure; Check NTC on return; Check that pump is wired into appliance and not from programmer. This would cause no pump overrun.
F25 (error solution f25)Maximum temperature rise slopePossible external pump failure; Air in system restricting movement of water. Insufficient circuit flow
F26Maximum delta tCheck NTC on return; System fault - too restrictive?; Possible pump failure

Vaillant ecoTEC PLUS SERIES boiler error codes

d.00Heating partial load
d.01Water pump return water time for heating mode
d.02Max. blocking time heating at 20°C Flow temperature
d.03Drinking water flow temperature reading (800 series only)
d.04Storage temperature reading (only 600 series)
d.05Flow temperature target value
d.06Drinking water temperature target value
d.07Warm start temperature target value (800 series only) Storage temperaturetarget value (600 series only)
d.08Room thermostat at terminal 3-4
d.09Flow target temperature from external analogue regulator to terminal 7-8-9/eBus
d.10Status internal heating pump
d.11Status external heating pump
d.12Status external storage charging pump
d.13Status external circulation pump
d.22Hot water request, Terminal C1/C2, impeller
d.25Storage charging/warm start through warm start clock regulator/release timer
d.40Flow temperature
d.41Return temperature
d.47Outside temperature (with connected VRC 410s)
d.67Remaining burner locking time
d.76Appliance variant (device specific number)
d.90Digital regulator status
d.91DCF status with connected external probe with DCF77 receiver
d.97Activation of the second diagnosis level
d.17Heating flow/return regulation changeover
d.18Pump mode (return flow)
d.19Only in ecoTEC plus: Operating modes of the two-stage heating pump
d.26Changeover option relay to BMU
d.27Changeover accessory relay 1
d.28Changeover accessory relay 2
d.30Control signal for both gas valves
d.33Fan speed target value
d.34Fan speed actual value
d.35Position of priority reverse valve (only 800 series)
d.44Ionisation current
d.50Offset for minimum speed
d.60Number of temperature limiting cut-offs
d.61Number of fuel automatic system faults
d.64Average ignition time
d.65Maximum ignition time
d.68Successful ignitions in the first attempt
d.69Successful ignitions in the second attempt
d.70Set priority-changeover valve position
d.71Target value max. heating flow temperature
d.72Pump return flow time after charging an electronically controlled hot water storage (also warm start and charging through C1-C2)
d.73Offset for warm start target value (only 800 series)
d.75Maximum charging time for a storage without own controller
d.77Storage partial load (storage charging capacity limit)
d.78Storage charging temperature limit (target flow temperature in storage mode)
d.80Heating operating hours
d.81Water heating operating hours (800 series only)
d.82Hystereses in heating mode
d.83Hystereses in hot water operation
d.84Maintenance indicator: Number of hours until the next maintenance
d.93DSN appliance variant setting
d.95eBus address
d.96Factory setting
NTC broken, NTC cable broken. Defective connection at NTC. Defective connection at electronics
F.01Return-NTC: NTC broken. NTC cable broken. Defective connection at NTC. Defective connection at electronics
F.02 (error solution f2)Drinking water outlet probe stopped (<-10 °C) (800 series only)
F.IOShort circuit - flow-NTC (< 130 °C)
F.11Short circuit - return-NTC (< 130 °C) NTC defective
F.13Short circuit in tank sensor
F.20 (error solution f20)Safety temperature limiter addressed
(error solution f22)
Dry fire
F.23 (error solution F23)Water shortage, temperature spread between flow and return probe too large
(error solution f24)
Water shortage, temperature rise too quick
F.25 (error solution f25)Flue gas safety temperature limiter addressed
F.27Secondary light, the ionisation signal reports a flame in spite of gas valve being turned off
(error solution f28)
Appliance does not start: Attempts to ignite during star failed
F.29(error solution f29)Flame goes off during operation and subsequent ignition attempts failed
F.32Fan speed variation (too high on start)
F.60Gas-valve control + defective
F.62Gas valve shutoff delay defective
F.63EEPROM error
F.64Electronics/sensor fault
F.65Electronics temperature too high
F.70No valid DSN in Al and/or BMU
F.71Flow sensor reports constant value
F.72Flow and/or return sensor fault
F.73Water pressure sensor or cable harness hydraulics defective
F.74Water pressure sensor or cable harness defective
(error solution f75)
No sudden change in pressure was detected on turning on the pump
F.76Overheating protection on primary heat exchanger triggered, damage in primary heat exchanger

Vaillant TURBOmax Plus SERIES boiler error codes

F.00Flow-NTC:Flow-NTC cable defective/broken NTC faulty
- NTC broken
- NTC cable broken
- Defective connection at NTC
- Defective connection at electronics
F.01Return-NTC:Return-NTC cable defective/broken NTC faulty
- NTC broken
- NTC cable broken
- Defective connection at NTC
- Defective connection at electronics
F. 10Short circuit - flow-NTC (< 130 °C)NTC- plug shorted to casing NTC defective
F. 11Short circuit - return-NTC (< 130 °C)
F.20 (error solution f20)Over heat cut off activatedMaximum temperature exceeded
(error solution f22)
Low water or no water in applianceNo water in system Pump defective Pump lead defective
F.27no demand to gas valveElectronic board defective Gas valve defective
(error solution f28)
Boiler goes to lock outNo gas Insufficient gas
Incorrect gas valve adjustment Electrode defective Ignition lead defect Electronic igniter defective
F.29(error solution f29)Flame extinguished re-ignition unsuccessfulGas supply absent or insufficient
F.42Faulty cable loomFaulty or incorrect loom fitted
F.60 to F.67Irreversible electronic system malfunctionElectronic system defective