BoilerFaultCodesTechnical description
Main burner fails to light and pilot is extinguished when pressure on the control knob is released - Partially blocked pilot injector.
What causes this fault?
This fault occurs when the pilot flame is too small or weak to properly heat the safety sensor, known as a thermocouple. The most common reason is a buildup of dust or debris inside the pilot injector, which restricts the gas flow and prevents the boiler from detecting that it is safe to stay on. Because the sensor doesn't get hot enough, it automatically cuts the gas supply as a safety precaution the moment you stop pressing the start button.
This issue often comes to light in autumn when the boiler is turned back on after being idle over the summer, as settled dust is more likely to cause a blockage then.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.