Gas Oven Won't Light Or Stay Lit

What's happening?

A gas oven lights in the same stages as a fire: a spark or a pilot lights the burner, and a flame failure device, a thermocouple, proves the flame before it lets the gas run on. If the oven will not light at all, the question is whether gas is reaching the cooker, which the hob tells you for free. If the hob lights and the oven does not, the fault is in the oven's own burner, igniter or valve. An oven that lights while you hold the knob and goes out when you let go has a flame failure device that is not getting enough heat or has failed. One that clicks and does not light has no gas getting to the burner, or a spark in the wrong place. Gas can collect in an oven that has not lit, which is why repeated attempts are not safe.

What usually causes it?

• The cooker's isolation valve, or the meter, turned off or out of credit
• A dirty or misaligned oven igniter, or one that has stopped sparking
• A burner with blocked ports from spilled food or grease
• A flame failure thermocouple that is worn or not heating properly
• A faulty oven thermostat or control valve
• A pilot light that has gone out or a blocked pilot jet on an older oven

Is it dangerous?

Medium. An oven that does not light can fill with unburnt gas. Do not try repeatedly, and never light it with a match or lighter unless the manufacturer's instructions describe a manual lighting method. Stop after two attempts, leave the door open and the room ventilated for several minutes. If you smell gas, leave the property and call 0800 111 999 (0800 002 001 in Northern Ireland).

Can I fix it myself?

Check the hob lights, which shows gas is reaching the cooker. Check the isolation valve on the gas pipe behind or beside the cooker is open: the lever should run along the pipe. Check prepayment credit. Clean spills from the oven floor and burner area when cool, without poking into the burner holes. Follow the manufacturer's lighting steps and hold the knob for the stated time. Leave the burner, igniter, thermocouple and valve to a Gas Safe registered engineer.

When should you call a gas engineer?

Call a Gas Safe registered engineer if the oven will not light after two attempts, goes out when released, smells of gas or burns with a yellow flame, or if only the oven fails while the hob works. Stop using it until it has been checked.

What will the gas engineer actually do?

• Check the gas supply and pressure at the cooker and the isolation valve
• Test and replace a failed igniter, electrode or thermocouple
• Clean the burner and check the flame picture is blue and steady
• Test the oven thermostat and valve and replace what has failed
• Check the flame failure device cuts the gas when the flame is lost
• Test for gas tightness and confirm the oven lights first time and holds temperature

Who fixes this

• Gas appliance repair
• Gas cooker and hob installation

Questions people ask

Sources & References

1. HSE: domestic gas safety, homeowner FAQs
2. Gas Safety (Installation and Use) Regulations 1998
3. NHS: carbon monoxide poisoning