Nobody likes to see an error code flash up on their boiler. It means there is another job to put on your ‘to do’ list! Before you panic and ring a Gas Safe registered engineer to fix the problem, it is worth familiarising yourself with some of the common errors that can occur in case it is an easy fix that can be done by a member of your household. Below, we have listed some of the common error codes that appear on Vaillant boilers and what they mean.
Vaillant Turbomax Plus 824/828E error codes
| Fault code | Possible cause | Meaning |
| F.00 | NTC FAULTS | This means that your Flow NTC (Negative Temperature
Coefficient Thermostat) cable is either defective or broken and needs to be replaced |
| F.01 | NTC FAULTS (feed temperature
sensor) – faulty connection and open circuit. |
This means that your Flow NTC (Negative Temperature
Coefficient Thermostat) cable is either defective or broken and needs to be replaced |
| F.10 | NTC FAULTS (feed temperature
sensor) – short circuit |
|
| F.11 | ||
| F.13 | NTC FAULTS (feed temperature
sensor) – short circuit |
|
| F.20 | NTC FAULTS (feed temperature
sensor) |
Your boiler has exceeded the maximum temperature and needs to be allowed to cool down |
| F.22 | DRY FIRE, LOW WATER IN
SYSTEM/OVERHEAT |
This means that there’s either no water in your system, you have a defective pump or the pump lead is defective |
| F.24 | LOW WATER, OR PUMP
FAILURE/BLOCKAGE |
Your pump could be obstructed, running at low capacity, or there could be air trapped in your appliance. Additionally, the pressure in your system might be too low. |
| F.28 | NO IGNITION/IGNITION
PROBLEM |
This means there’s either insufficient gas in the system, a
defective electrode, ignition lead or electronic ignitor |
| F.29 | FLAME EXTINGUISHED.
FAN/FLUE PROBLEM/GAS |
Your flame, or pilot light has gone out. Check your flue duct or gas supply to see if there is a problem there. |
| F.60 | GAS VALVE CONTROL – DEFECTIVE | Your cable loom which connects to your gas valve might have short circuited. Alternatively, you could have a defective gas valve assembly or electronic control system. |
| F.61 | GAS VALVE CONTROL – DEFECTIVE | Your cable loom which connects to your gas valve may have short circuited. Alternatively, you could have a defective gas valve assembly or electronic control system. |
| F.62 | DEFECTIVE GAS VALVE
CLOSURE MECHANISM |
Your boiler has exceeded the maximum temperature and needs to be allowed to cool down |
| F.63 | EEPROM (Electrically Erasable
Programmable Read-Only Memory) ERROR |
This is an electronic fault within your system. |
| F.64 | ELECTRONIC
SYSTEM/SENSOR FAULT |
Your flow or back flow NTC has suffered a short circuit, or an electronic fault |
| F.65 | ELECTRONIC SYSTEM
TEMPERATURE TOO HIGH |
This can happen because of an external heat source or an
electrical fault |
| F.67 | ELECTRONIC FAULT IN FLAME SYSTEM |
Vaillant error codes F28 and F29
If your Vaillant boiler is showing either error code F28 or F29 then the condensate pipe has frozen.
Vaillant EcoMax Pro 18/29E error codes
| Fault code | Possible cause |
| F.1 | Lack 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.4 | Ignition fault |
| F.5 | The system has suffered a fault due to overheating. |
| F.6 | Your flow NTC has developed a fault. |
| F.17 | Check the polarity of your system. |
| F.24 | Pump-related faults – the pump could have failed, it may have over run or there could be an issue with the airlock |
Vaillant Eco Max Pro 828E error codes
| Fault code | Possible cause |
| F.00, F.04, F.05, F.10, F.14, F.15 | Lack 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.21 | The pilot flame has failed. |
| F.22 | There is insufficient water in your system. |
| F.11 | A blockage in the appliance is preventing the system from flowing as it should. |
| F.12 | A blockage in the appliance is affecting the system’s pressure. |
| F.13 | The appliance is blocked because of a water deficiency. |
Vaillant EcoTEC 65Kw error codes
| Fault code | Possible cause |
| S.0 | Heating issue, no heat demand |
| S.1 | Fan start-up error |
| S.2 | Pump flow error |
| S.3 | Heating mode error – ignition problem |
| S.4 | Heat mode – burner on error |
| S.6 | Heating mode – fan overrun error |
| S.7 | Heating mode – pump overrun error |
| S.8 | Heating remaining cut off for XX amount of time |
| S.31 | No heat demand summer operating mode |
| S.34 | Heating mode frost protection error |
| S.20 | Hot water requirement error |
| S.22 | Hot water handling pump flow error |
| S.24 | Hot water operation burner is on |
| S.85 | Service message quantity of circulation water |
Vaillant EcoTEC Pro / EcoTEC plus error codes PT1
| Fault code | Possible cause |
| F.00 / F.0 | Flow temperature sensor interruption |
| F.01 / F.1 | Return temperature sensor interruption |
| F.10 | Flow NTC short circuit |
| F.11 | Return NTC short circuit |
| F.20 | Safety switch off temperature limiter |
| F.22 | Safety switch off low water pressure |
| F.23 | Safety switch off temperature difference too great |
| F.24 | Safety switch off temperature is rising to fast |
| F.25 | Safety switch off flue gas temperature too high |
| F.26 | Error with gas valve – possible no function |
| F.27 | Safety switch off flame simulation |
| F.28 | Failure during start up – ignition unsuccessful to start |
| F.29 | Failure during operation – re-ignition unsuccessful |
| F.32 | Fan error |
| F.49 | eBUS error – possible short circuit |
| F.61 | Error with gas valve regulation |
| F.62 | Error with gas valve – switch off delay |
| F.63 | EEPROM error |
| F.64 | Electronics / NTC error |
| F.65 | Electronic temperature error could be overheating due to external influences |
| F.67 | Electronics flame signal error |
| F.68 | Unstable flame signal error air in gas |
| F.70 | Invalid device specific number (DSN) |
| F.71 | Flow NTC error – flow temperature sensor signal constant value |
| F.72 | Flow return NTC error – temperature difference too great |
| F.73 | Water pressure sensor signal in the wrong range, it is too low |
| F.74 | Water pressure sensor signal outside correct range, the sensor signal is too high |
| F.75 | Error with pressure – no pressure change detection when starting the pump |
| F.76 | Overheating protection on – primary heat exchanger has responded |
| F.77 | Flue non return flap condensate pump error |
| F.78 | Interruption to DHW outlet sensor at external controller |
| F.83 | Flow and or return temperature sensor error |
| F.84 | Error with flow/return temperature sensor temperature changing error |
| F.85 | Error with flow and return temperature, sensor incorrectly fitted |
| CONNECTION | No communication with the PCB |
| S.00 | Heating mode error – no heat demand |
| S.01 | Heating mode fan start-up |
| S.02 | Heating mode error – water pump running |
| S.03 | Heating mode – ignition sequence error |
| S.04 | Heating mode – burner ignited |
| S.06 | Heating mode – fan overrun error |
| S.07 | Heating mode – pump overrun error |
| S.08 | Heating remaining cut off time xx minutes |
| S.10 | Hot water demand via impeller sensor |
| S.11 | DHW mode fan start up error |
| S.13 | DHW mode ignition error |
| S.14 | Hot water demand via fan sensor error |
| S.15 | DHW mode pump and fan overrun |
| S.16 | DHW mode – fan overrun error |
| S.17 | DHW mode – pump overrun error |
| S.20 | DHW mode – burner on error |
| S.21 | DHW mode – fan start up error |
| S.22 | DHW demand – error pump running |
| S.23 | DHW ignition error |
| S.24 | DHW mode – burner error |
| S.25 | DHW mode – pump or fan overrun error |
| S.26 | DHW mode – fan overrun |
| S.27 | DHW mode – fan overrun |
| S.28 | DHW mode – fan overrun |
| S.30 | Room thermostat is blocking heating mode |
| S.31 | No heat demand boiler in summer operating mode |
| S.32 | Waiting period because of fan speed deviation |
| S.34 | Heating mode frost protection error |
| S.39 | Burner off contact has been triggered this could be because of contact thermostat or condensate pump |
| S.40 | Comfort safety mode active |
| S.41 | Water pressure > 2.8 bar |
| S.42 | Flue non return flap return signal blocks burner operation |
| S.46 | Comfort safety mode flame loss at minimum load |
| S.53 | Boiler is in waiting period of modulation f block function due to water shortage |
| S.54 | Boiler is in waiting period of operation, blocking function as a result |
| S.57 | Waiting period comfort safety mode |
| S.58 | Modulation limitation due to noise / wind error |
| S.61 | Gas family check unsuccessful |
Vaillant EcoTEC Plus regular gas boiler error codes
| Fault code | Possible cause |
| S.20 | Warnstar demand |
| S.21 | Fan running |
| S.22 | Pump running |
| S.23 | Ignition sequence |
| S.24 | Burner ignited |
| S.25 | Fan and water pump running |
| S.26 | Fan overrun |
| S.27 | Pump overrun |
| S.28 | Anti-cycling mode |
| S.30 | No heating demand from external controls |
| S.31 | Central heating thermostat knob turned off |
| S.32 | Heat exchanger antifreeze active as fan speed variation is too high |
| S.34 | Anti-frost mode is active |
| S.36 | Not heating demand form low voltage |
| S.41 | Water pressure greater than 2.9 bar |
| S.42 | Response from accessory module or defective condensate pump is blocking burner operation |
| S.53 | Appliance is within the waiting period of the block operation function due to water shortage |
| S.54 | Appliance is within the waiting period of the block operation due to water shortage |
| S.96 | Return sensor error |
| S.98 | Flow return sensor check is running demand is block |
| D.0 | Heating part load error |
| D.1 | Water pump overrun – time for heat mode |
| D.2 | Max burner anti-cycling period at 20c flow temperature |
| D.3 | Hot water flow temperature reading |
| D.4 | Current temperature for warm stat sensor |
| D.7 | Warm start temperature target value |
| D.8 | External controls heat demand |
| D.9 | Flow target temperature from external analogue regulator terminal |
| D.10 | Status internal heating pump error |
| D.11 | Status external heating pump error |
| D.12 | Cylinder charging pump via accessory module |
| D.13 | Hot water circulation pump |
| D.22 | Hot water demand |
| D.23 | Summer/Winter function |
| D.25 | Hot water activation via ebus control |
| D.30 | Control signal for both gas valves |
| D.33 | Fan speed target value |
| D.34 | Fan speed actual value |
| D.36 | Hot water flow sensor |
| D.40 | Flow temperature target value |
| D.41 | Return temperature actual value |
| D.44 | Digitised ionisation potential error |
| D.47 | Outside temperature with weather compensator – Vaillant controller only |
| D.76 | Remaining burner anti-cycling time in min |
| D.90 | Digital regulator status |
| D.91 | DCF status with connected external probe |
| D.97 | Activation of the second diagnostic level |
| D.17 | Heating glow return regulation |
| D.18 | Pump mode return |
| D.19 | Operating modes of the two speed heating pump |
| D.20 | Maximum set value for target cylinder |
| D.27 | Switching accessory relay 1 |
| D.28 | Switching accessory relay 2 |
| D.50 | Offset for minimum speed |
| D.51 | Offset for maximum speed |
| D.58 | Activation of solar reheating |
| D.60 | Number of safety temperature cut off |
| D.61 | Number of unsuccessful lockouts |
| D.64 | Average ignition times |
| D.65 | Maximum ignition time |
| D.68 | Unsuccessful ignitions in the first attempt |
| D.69 | Unsuccessful ignition for the second time |
| D.70 | Set diverter valve position |
| D.71 | Maximum setting of heater control knob |
| D.72 | Pump overrun time after warm start |
| D.73 | Off set for warm start target value |
| D.75 | Maximum charging time for a storage without own controller |
| D.77 | Limitation of cylinder charging in output in kW |
| D.78 | Limitation of cylinder charging in output in C |
| D.80 | Operating hours heating |
| D.81 | Operating hours hot water generation |
| D.82 | Burner start up in heating mode |
| D.83 | Burner start up in hot water mode |
| D.84 | Maintenance indicator – number of hours until the next maintenance |
| D.93 | DSN appliance variant setting |
| D.96 | Factory setting |
| P.00 | The heating circuit and hot water circuit are purged |
| P.01 | Maximum load test program error |
| P.02 | Minimum load test program |
| P.06 | Filling mode test program |
