Clean the piezo and thermocouple

Spark test, then clean the tips

The help centre ("I'm having trouble lighting" and "The flame is cutting out").

1. Disconnect the regulator and wait 5 minutes.
2. Watch the piezo tip while you push and turn the knob slowly to the click. A spark means the ignition works and any problem is the gas.
3. With the oven cold and gloves on, blast compressed air at the piezo tip to clear soot, flour and debris.
4. Wipe the thermocouple with a dry paper towel, or blow it clean.
5. Reconnect, leak test and light it, holding the knob in for 5 seconds.