Vaillant Boiler Fault Codes / Error Codes and How to Fix Them?
Vaillant uses several fault codes to depict the problem, most related to the vent system and its integrated pressure relief valve. In this article, we’ll look at some common Vaillant Ecotec plus fault codes and other Vaillant models including Ecomax and Turbomax so that you can understand what the codes mean and what you can do to fix any issues they may cause.
Fault codes are codes that indicate a problem with the central heating system in your home. They’re a diagnostic mechanism because they provide a numerical list of the various things that could be wrong with your boiler. Vaillant boiler fault codes can help you identify the source of the malfunctioning circuits as quickly as possible. You may then get the boiler fixed swiftly so that it can once again heat your home.
Important Disclaimer
This guide intends to help you identify the common Vaillant boiler problems and understand the fault codes associated with them. However, this guide does not provide solutions as some of the solutions can pose a safety risk and to solve the problem you either contact Vaillant or a certified Gas Safe Registered engineer.
List of Vaillant boiler fault and error codes
Fault codes are a series of letters and numbers displayed on your Vaillant boiler’s control panel. These codes indicate a problem that needs to be addressed. The following tables list common fault codes for various Vaillant boiler models.
1. Vaillant EcoTec 65kw Boiler Fault Code
2. Vaillant Ecotec pro 28 fault codes/ EcoTEC Plus Boiler Codes
- F.00 / F.0
- F.01 / F.1
- F.10
- F.11
- F.20
- F.22
- F.23
- F.24
- F.25
- F.26
- F.27
- F.28
- F.29
- F.32
- F.49
- F.61
- F.62
- F.63
- F.64
- F.65
- F.67
- F.68
- F.70
- F.71
- F.72
- F.73
- F.74
- F.75
- F.76
- F.77
- F.78
- F.83
- F.84
- F.85
- CONNECTION
- S.00
- S.01
- S.02
- S.03
- S.04
- S.06
- S.07
- S.08
- S.10
- S.11
- S13
- S.14
- S.15
- S.16
- S.17
- S.20
- S.21
- S.22
3. Vaillant EcoTEC Plus Regular Boiler Gas Boiler Error Codes
- D.0
- D.1
- D.2
- D.3
- D.4
- D.5
- D.7
- D.8
- D.9
- D.10
- D.11
- D.12
- D.13
- D.15
- D.22
- D.23
- D.24
- D.25
- D.30
- D.33
- D.34
- D.35
- D.40
- D.41
- D.44
- D.47
- D.76
- D.90
- D.91
- D.97
- D.98
- D.14
- D.17
- D.18
- D.20
- D.26
- D.27
- D.28
- D.50
- D.51
- D.60
- D.61
- D.64
- D.65
- D.67
- D.68
- D.69
- D.70
- D.71
- D.72
- D.75
- D.77
- D.78
- D.80
- D.81
- D.82
- D.83
- D.84
- D.93
- D.96
4. Vaillant EcoMax Pro Boiler Fault Codes 18/28E
| Code | Description |
|---|---|
| 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 X 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 |
| 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 switches off temperature limiter |
| F.22 | Safety switches off low water pressure |
| F.23 | Safety switches off temperature difference too great |
| F.24 | Safety switches off temperature is rising too fast |
| F.25 | Safety switches off flue gas temperature too high |
| F.26 | Error with gas valve – possible no function |
| F.27 | Safety switches 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 signals 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 X minutes |
| S.10 | Hot water demand via impeller sensor |
| S.11 | DHW mode fan start up error |
| S13 | 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 – pump overrun |
| S.28 | Hot water burner anti-cycling time |
| 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 |
| Fault Code | Possible Cause |
|---|---|
| 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.5 | Set value of flow temperature or target value of return |
| 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.15 | Pump speed actual value |
| D.22 | Hot water demand |
| D.23 | Summer/Winter function |
| D.24 | Not relevant |
| 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.35 | Not relevant |
| 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.98 | Telephone a heating engineer |
| D.14 | Pump speed target value |
| D.17 | Heating flow return regulation |
| D.18 | Pump operating mode |
| D.20 | Maximum set value for target cylinder |
| D.26 | Additional relay control ecoTec |
| 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.60 | Number of safety temperature cut offs |
| D.61 | Number of unsuccessful lockouts |
| D.64 | Average ignition times |
| D.65 | Maximum ignition time |
| D.67 | Remaining burner anti-cycling 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.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 temperature in Celsius |
| D.80 | Operating hours heating |
| D.81 | Operating hours hot water generation |
| D.82 | Burner starts up in heating mode |
| D.83 | Burner starts 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 |
| Fault Code | Possible Cause |
|---|---|
| F.1 | Lack of gas, a fault with the ignition or flue – 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 overrun or there could be an issue with the airlock. |
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How to fix common Valliant Boiler fault and error codes
Leaks in the Boiler
F22 possible trouble codes
Leaks in boilers can occur for a variety of causes, including rusted or malfunctioning components, damaged seals, or high pressure. Boiler leaks, unfortunately, have the potential to inflict significant damage to your boiler’s electrical components as well as your property. If you suspect that your boiler (or any other component of your heating system) is leaking, contact a Gas Safe specialist right away.
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Hot water without heat
If your Vaillant boiler supplies hot water but no heat, you may be dealing with one of the following problems:
- The radiators are suffocating with air.
- Diverter valve isn’t working properly
- Other boiler or heating system malfunctions
The first two causes are quite simple to address. Bleeding your radiators will let trapped air out, and it won’t take long to figure out if your combi isn’t configured to create heat. The last one, on the other hand, will necessitate the intervention of a Gas Safe engineer.
Low boiler pressure
F22 is the possible fault code
Vaillant boilers, like all other boilers, suffer from low pressure due to leakage. If that’s the source of the low pressure, the leak is the real problem. However, a defective pressure sensor could cause your boiler pressure to appear low.
No hot water no heat
F20-F25 is the possible fault code
It’s possible that your Vaillant boiler isn’t producing hot water or heat because:
- For safety reasons, the boiler has been turned off.
- Your boiler isn’t getting any power or gas.
- There’s another issue that’s hurting your complete system.
It’s time to call a Gas Safe engineer to evaluate the situation if you’ve ruled out the obvious, such as a lack of electricity or gas to your residence, or a tripped circuit.
Frozen condensate pipe
F28-F29 is the possible fault code
If your Vaillant doesn’t turn on during chilly winter season, the condensate line may have iced over. The boiler will shut out unless the pipe is unblocked, which is a safety feature. A frozen condensate pipe may usually be thawed out using warm water.
After knowing about all these Vaillant boiler fault codes and error codes, if you are still unable to identify the issue, contact a qualified Gas Engineer for advice or consider replacing the boiler if necessary.
Basic boiler safety tips
I hope you have now gained the knowledge to identify Vaillant boiler fault codes. However, there are a few basic safety tips that you should practice regularly which are the following:
- Never attempt to repair a gas boiler yourself unless you are a Gas Safe registered engineer. Gas leaks and faulty wiring can be dangerous.
- Turn off the boiler and gas supply if you suspect a leak or malfunction.
- Be aware of the signs of carbon monoxide poisoning (headaches, nausea, dizziness) and evacuate your home immediately if you suspect a CO leak.
- Schedule regular boiler maintenance by a gas-safe engineer to prevent problems and ensure safe operation.
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FAQs
What is the Vaillant boiler f75 fault code?
The official explanation for the Vaillant error F75 is that when the pump starts up, no pressure change is observed. This means that when the pump is running, the boiler is unable to detect the proper pressure. In general, this indicates that either the pressure sensor or the pump itself is malfunctioning.
What is the Vaillant boiler f22 fault code?
The Vaillant F.22 error number indicates low water pressure in your boiler. You’ll need to adjust the water pressure to the proper level to fix the problem and have your boiler working properly again.
What is the Vaillant combi boiler fault code f28?
When your boiler fails three ignition attempts, the F28 code appears, causing the boiler to shut down and turn off. The F28 error code is officially defined by Vaillant as an ignition failure.
What is the Vaillant boiler f20 fault code?
F20, this error code indicates that your boiler has overheated and requires time to cool down and restore to a safe operating temperature. This could be the result of a faulty ground connection between the cable and the boiler.
What is the Vaillant ecoMAX boiler f25 error code?
The ecoMAX Plus F. 25 fault indicates a safety shut-off. The temperature of the flue gas is too high in this scenario. STB is a flue gas temperature limitation found in Ecotec Plus boilers.
What is the Vaillant boiler error code f61?
If your Vaillant boiler displays an F61 error code, it signifies the gas valve is broken. Because this is a potentially dangerous error, you’ll want to make sure it’s fixed as soon as possible.
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