All 18 Vaillant boiler codes
- F.22Water pressure in the heating system is too low
- F.28Boiler failed to light
- F.29Flame went out and the boiler couldn't relight
- F.20Overheat safety cut-out has tripped
- F.23Too big a gap between flow and return temperature
- F.24Temperature rising too fast
- F.25Flue gas temperature too high
- F.27Flame detected with the burner off
- F.75No pressure rise when the pump starts
- F.00Flow or return temperature sensor not reading
- F.10Temperature sensor short circuit
- F.13Hot water cylinder sensor short circuit
- F.32Fan speed out of range
- F.61Gas valve control fault
- F.62Flame took too long to go out
- F.68Unstable flame
- F.70Invalid device code after a repair
- F.83Dry fire: no temperature change when the burner lit
About Vaillant boiler error codes
Vaillant is a German heating company founded in Remscheid in 1874, and one of the most common gas boiler brands in the UK and Ireland. Its ecoTEC boilers show faults as an F code on the display, such as F.28 or F.022 on newer models, and many of them can be cleared with the reset button once the cause is fixed.
How to read Vaillant boiler codes
Vaillant shows faults as F followed by a number. Depending on the model and display, you'll see two digits (F.22, F.28) or three (F.022, F.028); this page uses the two-digit form. Codes starting with S. are status messages rather than faults. On current ecoTEC plus models an N. code means limp-home mode: the boiler can still run safely, but an engineer needs to look at it.
To reset, press and hold the reset button for more than 3 seconds; on current ecoTEC plus models a short press only switches standby on or off. For an ignition lockout Vaillant allows three reset attempts. After that, call a Gas Safe registered engineer (a Registered Gas Installer in Ireland). Anything behind the front casing is engineer work, and Vaillant's operating manual tells owners not to alter the boiler, its gas, water and electrical supply lines, the flue or the condensate system, or tamper with any safety device.
If you smell gas: no light switches, plugs or flames, open doors and windows, turn the gas off at the meter's emergency control valve if you can do it safely, get everyone out and phone your gas emergency number from outside. A carbon monoxide alarm, or people feeling unwell and you suspect CO, gets the same response: switch the boiler off, ventilate, leave and call.
Of the 18 codes on this page, 1 usually have a simple fix you can do yourself, and 14 usually need a technician. Each guide says which is which, so you don't pay for a service call you don't need, and you don't attempt a repair that isn't safe.
Before you start
- Write down the model name. It's printed on the front panel or on the data badge, and your operating manual names it too. Some code meanings depend on the range.
- Use the reset button. Your operating manual shows which button resets the boiler and how many times you may try. Don't keep pressing it if the same code returns.
- Look at the pressure gauge first. Vaillant, for one, asks for at least 1 bar with the heating cold and about 1.5 bar as the usual figure; your manual gives the number for your boiler.
- If you smell gas, open the windows, don't touch switches, turn the gas off at the meter if you can and call your gas emergency number from outside.