Hob burner goes out when you release the knob: the flame-failure device

This is the most common hob complaint we take, and it is a safety feature doing its job — just doing it when you do not want it to.

What the device does

A small metal probe sits in the flame at each burner. When it is hot, it holds the gas valve open. If the flame goes out, it cools and the gas shuts off within seconds. That is what stops a blown-out burner filling the kitchen.

Why it cuts the gas when the flame is fine

• The probe is dirty — grease or boil-over coating it, so it never gets hot enough
• The probe has shifted out of the flame — knocked while cleaning
• The probe has worn out and no longer generates enough signal
• The magnet valve it controls has weakened

What you can do

Hold the knob in for a full ten seconds after lighting. If the burner then stays lit, the probe is just slow — usually dirty. Let the hob cool completely and wipe the probe with a dry cloth. Do not bend it.

What needs a visit

If a ten-second hold does not help, or if the probe is visibly bent or corroded, the thermocouple needs replacing. They are standard parts. If a new one still cuts out, the valve behind it is the fault.

Do not defeat the device — some online advice suggests wedging the knob or removing the probe. It exists because a blown-out hob burner in a closed kitchen is genuinely dangerous.