Is your boiler displaying an error code? Find your boiler manufacturer or search for the code below. Discover what common faults may indicate, which checks are safe to carry out and when to contact a qualified heating engineer.
Enter the code displayed on your boiler or select its manufacturer. Browse common error codes, understand possible causes and find out when professional assistance may be required.
Meaning: On applicable models, the boiler has not detected a flame.
Possible causes: Ignition, flame sensing, gas supply or related components.
Next step: Check the exact model instructions. Persistent ignition faults require professional diagnosis.
Boiler ignition troubleshooting →Meaning: The temperature safety limiter has activated on applicable models.
Possible causes: Circulation, pump, system pressure or temperature-related problems.
Next step: Avoid repeated resets and arrange an engineer if the fault persists.
Meaning: Insufficient water or low system pressure has been detected.
Possible causes: Pressure loss, pressure sensor or associated system faults.
Next step: Check the displayed pressure. Only repressurise if your model instructions permit it and you know the procedure.
Boiler losing pressure guide →Meaning: The boiler has not detected a flame during ignition.
Possible causes: Gas supply, ignition components, condensate blockage or other internal faults.
Next step: Follow the manufacturer instructions. Recurring faults need an engineer.
Boiler won't ignite guide →Meaning: The expected pressure change was not detected when the heating pump started.
Possible causes: Pressure sensor, pump, air in the system or insufficient pressure.
Next step: Professional diagnosis is recommended.
Meaning: Ignition lockout or flame loss on applicable Ideal boilers.
Possible causes: Ignition, flame detection or gas supply problems.
Next step: Follow your model's instructions and seek an engineer if the fault returns.
Ignition troubleshooting →Meaning: The boiler has detected low heating system pressure.
Next step: Check the pressure gauge and follow the manufacturer's guidance for your model. Repeated pressure loss should be investigated.
Low pressure troubleshooting →Meaning: The boiler has experienced flame loss.
Next step: Check the relevant model instructions. If the fault returns, arrange professional diagnosis.
Meaning: A fan-related fault has been detected on applicable models.
Next step: Do not attempt to access the fan or internal components. Contact a qualified engineer.
Meaning: A flow thermistor or temperature-sensing fault has been detected on applicable models.
Next step: Internal sensor faults require professional investigation.
Meaning: A gas supply or ignition-related fault has been detected on applicable models.
Next step: Consult your manual. If the error returns, arrange an engineer. If you smell gas, follow emergency gas safety procedures.
Ignition troubleshooting →Meaning: The maximum temperature or safety thermostat limit has been reached on applicable models.
Next step: Do not attempt internal repairs. Arrange professional inspection if the fault persists.
Meaning: Low heating system water pressure has been detected.
Next step: Check the displayed pressure and follow the instructions for your exact boiler model.
Pressure loss guide →Meaning: A water circulation problem has been detected on applicable models.
Next step: Circulation problems may involve internal components. Arrange professional diagnosis.
Meaning: A fan-related fault has been detected on applicable models.
Next step: Internal inspection should be carried out by an appropriately qualified engineer.
Meaning: Dry-fire protection has activated on applicable models.
Next step: Do not repeatedly reset the appliance. Arrange professional investigation.
Meaning: On applicable tank boiler models, a domestic hot water temperature sensor fault has been detected.
Next step: Arrange professional sensor diagnosis.
Can't find your code? Our heating engineers can help identify the problem.
Ask an Engineer →A boiler fault code is a combination of letters or numbers displayed when the appliance detects an operating problem. Codes can relate to ignition, pressure, circulation, overheating, sensors or other components.
The same code can have different meanings across manufacturers and boiler models. Identifying the exact appliance is essential before deciding what the error indicates.
It identifies a condition detected by the boiler, not necessarily the component responsible. A qualified engineer may need to investigate the underlying cause.
No fault code showing? Explore common boiler problems and find out what you can safely check.
A reset may restore operation after a temporary fault, but it does not repair the underlying cause. Only reset your boiler if the manufacturer's instructions permit it for the fault displayed.
If the same code returns or the boiler repeatedly locks out, stop resetting it and arrange professional advice.
Do not attempt to reset an appliance if you suspect a gas leak, carbon monoxide, electrical damage, overheating or another serious safety issue. Follow the appropriate emergency guidance instead.
Answers to common questions about boiler error codes, resets and recurring faults.
No. Each boiler manufacturer uses its own fault-code system, and meanings may differ between models from the same brand. Always check your exact boiler model before interpreting a code.
Some temporary faults can be cleared through a manufacturer-approved reset or a basic external check. However, clearing a code does not necessarily resolve the underlying problem. Never attempt internal boiler repairs.
A recurring fault code usually indicates that the underlying issue has not been resolved. It may involve ignition, pressure, circulation or another component that requires professional investigation.
Not every boiler fault code indicates immediate danger. Some represent protective shutdowns or operating problems. However, suspected gas leaks, carbon monoxide or electrical faults require immediate safety precautions.
A fault code provides a useful starting point, but it does not always identify the exact failed component. Engineers may need to inspect and test the boiler to confirm the cause.
Boilers can develop problems without displaying an error. Symptoms such as pressure loss, no heating, no hot water, leaks or unusual noises can help identify the issue. Explore our troubleshooting guides or arrange an inspection.