Worcester Bosch Greenstar Junior 28i repair. Boiler not working in both hot water and central heating modes. You can hear fan starting but boiler does not ignite. After short while boiler goes into lockout mode and has blue light flashing (mostly off and then on for a short while) – please see video below to see how the blue light flashes. Also reset button is flashing.

According to Worcester Junior manual blue light flashing (mostly off, flashes on) with lock out reset button flashing can mean following:

• no gas or incorrect gas pressure
• gas valve faulty
• combustion CO2 levels out of range
• blocked flue
• blocked condensate pipe or frozen condensate pipe
• ignition electrodes or harness faulty
• pcb faulty

Generally slow flashing blue light with reset button flashing indicate ignition or combustion problem. Boiler either does not ignite or cannot establish stable combustion. Same fault codes can also mean problems with electronics (PCB) or spark generator.

First thing to check is to make sure that gas is on. Check if your prepaid meter has credit on it. Check if you get gas to other appliances such as gas hob if there is one. Check your condensate pipe for blockage or freezing in the winter.

In this case the fault was connected to a major component failure in the boiler and it had to be replaced.

Video below shows the boiler under fault conditions and also working correctly following repair.