Vaillant F27 Fault

Vaillant F27 Fault

The Vaillant F27 error code means that there is a problem with flame detection on the boiler when there is no flame. This happens because of irregularities in the ignition sequence or flame presence even if the system has not initiated the ignition or should have no flame. It may be caused by various things, but mostly related to faults in the flame detection device and electrical problems.
Reasons for F27 Error Code

Flawed Flame Detector: The burner’s flame detector which determines if a fire is lit could have been malfunctioning thereby causing it to send wrong signals to boiler control unit.

Electrical Interference: External electrical interference or issues within boiler electrical system could result into fake detection of fire flames.

Control Board Issues: Faulty readings or a signal being misinterpreted as indicating that fire is present can come about due to a fault existing on the printed circuit board (PCB) within your boiler.

Dirty or Misaligned Flame Sensor: Over time, dirt and misalignment may cause the sensor to incorrectly show that there is a presence of fire.

Troubleshooting and Fixing F27 Error Code

Check and Clean Flame Detector: Before anything else, inspect whether your flame detector is still new. In case it needs cleaning, clean it properly making sure that you follow manufacturer’s alignment details.

Watch Out for Electrical Interference: Try identifying any possible sources of electrical disturbances nearby your boiler then eliminate them if they are avoidable. Confirm that all electricity connections within your heating equipment remain intact and unharmed without failing in any way either through corrosion or wearing out.

Reset Your Boiler: Resetting its memory by pressing reset button helps clear temporary errors from boilers. Sometimes these temporary faults can be cleared by simply resetting the system altogether.

Consult Boiler’s Manual Booklet: Go through your boiler’s manual for specific troubleshooting tips applicable with regard to F27 error code. The handbook might offer further insights or methods of handling this problem.

Professional Diagnosis and Repair: This is why a Gas Safe registered engineer could be the best person to contact in case you want to diagnose complex problems associated with flame detection and electrical components. A professional can perform detailed diagnostics, make accurate assessment of your boiler and carry any necessary repairs or adjustments.

Timely Maintenance: Regular servicing by an expert technician will keep your boiler running optimally. Checking from time to time will prevent faults like F27 because it ensures that these equipment are kept clean, align them correctly and they have to be in their proper working condition.


The Vaillant F27 error code implies that there is a serious issue – false flame detection, therefore the boiler’s safety and efficiency should not be overlooked. While some basic checks as well as cleaning may be done at home owners’ level most solutions demand professional intervention. To avoid such faults and maintain high performance of your Vaillant boiler regular service and maintenance should never be ignored.