Vaillant F28 Error Code: What It Means and How to Fix It
F28 is the most common fault code on Vaillant boilers. It means ignition failure, which means the boiler tried to light but could not establish a flame. It is frustrating but usually fixable without a major repair.
What causes F28?
There are four main causes, and they are listed here in order of how likely they are:
1. Frozen condensate pipe
If it is cold outside (below freezing), this is the most likely cause. The condensate pipe runs from your boiler to an outside drain, and when it freezes, the boiler cannot discharge waste water and locks out. Pour warm water over the frozen section of pipe, then reset the boiler.
2. Gas supply interrupted
Check your other gas appliances. Does the hob light? If nothing gas powered is working, your gas supply may be off. Check the gas meter and make sure the emergency control valve is in the on position. If your supply has been disconnected, contact your gas supplier.
3. Faulty ignition electrode
The ignition electrode creates the spark that lights the gas. Over time, it can wear down, crack, or become covered in carbon deposits. When it cannot generate a strong enough spark, the boiler fails to ignite and shows F28. Replacing the electrode is a quick and relatively inexpensive repair.
4. Gas valve failure
The gas valve controls the flow of gas to the burner. If it is stuck or faulty, gas cannot reach the burner and the boiler will not ignite. This is a more significant repair but still common.
How to reset after F28
Press the button with the flame icon (with a line through it) and hold for 3 seconds. The boiler will attempt to reignite. If it fires up and stays running, monitor it over the next few hours. If F28 returns, do not keep resetting. Call an engineer and tell them the code.
Is F28 serious?
F28 itself is not dangerous. It is a safety lockout, which means the boiler has detected it cannot ignite safely and has shut down to protect you. The underlying cause needs fixing, but the lockout is the boiler doing its job.
Need help with your boiler? Our Gas Safe registered engineers cover the North East. Get in touch today or call 07579 760536.