This fault relates to Worcester Greenstar boilers and displays when the fan speed is too high. To fix this issue you can first try restarting the boiler as sometimes it can resolve itself. However, if this isn’t the case and the speed is still too high, you should contact an engineer to come and fix the problem.

The code B7 257 refers to an internal error or a potential problem with the control board. This means the electronics of the control board within the boiler aren’t working as they should. As this is an internal error, only a Gas Safe engineered should attempt to fix the issue.

This error code means that the control box or HCM is defective, which suggests that there is a fault with the control element that is responsible for regulating heat in the boiler. To fix this problem, you will need to contact a boiler engineer to check and possible replace the faulty HCM or control box.

If this code displays on your Worcester boiler it means that the pump is blocked or running with air in the system. This is an internal fault that can cause problems controlling the air to gas ratio. Resetting the boiler can sometimes resolve this or turning the box or heat control reset button off and on again. If this isn’t successful, you will need to contact an engineer to come and check the issue.

This code suggests that the primary flow is working at the minimum burner level, which means the flow of water through the boiler is too low to consistently maintain proper burner operation. When this has been detected, you should ensure the safety valve is between 1 and 1.5 pulses and the service mode on the burner control unit if this is the case. It might be that the temperature sensor needs replacing.

If this message displays on your boiler it means the temperature of the boiler is too high. So, the water that is circulating through the system is hotter than it should be. This can suggest that the safety temperature limiter has tripped and many need to be replaced. It can be fixed by restarting the boiler to trigger the low mains voltage, by doing so the high limit thermostat should be reset to prevent further overheating.

This code means there is a loss of ionisation signal detected before the burner starts up or during its operation. Essentially this means the boiler is struggling to detect the presence of a flame. If the temperature sensor has been fitted correctly, the pressure should be between 1.0 and 1.5 bars. The connections should be checked, and the boiler reset to resolve the issue.

This error code will appear if the burner control unit’s flow temperature sensor or hot water temperature sensor is excessively high. If the temperature sensor is defective, a professional heating technician will need to replace it.

If you see this code appear, it indicates that the signal from the heat exchanger temperature is out of range for the primary flow temperature. Therefore, the sensor that measures the heat exchanger temperature is giving unusual readings. This can be fixed by turning the modulating gas valve anticlockwise to trigger a reset position for the safety or flow temperature.

If you get this code on your Worcester boiler it means that your boiler’s water pressure is too low. If the problem relates to your domestic hot water, you might need to replace the vent system or pressure sensor. Also, if needed you should top up the water.

This code means a safety sensor has initiated an error and is recorded in the history menu, in other words, a safety element has detected a fault in the boiler. Simply restarting the boiler can sometimes clear this error but if not, it could imply there is a more serious issue that an engineer should check.

This error code means the boiler cannot properly ignite. You should check that gas supply is available to the boiler and that the gas valve is open. Check the ignition leads for any signs of damage or a blockage. If needed, you should contact and engineer for help finding the cause of the fault.