Burner Checks
When a La Cornue burner will not light, first confirm the gas is on and other burners work, which rules out the supply. Let the burner cool, then clean around the igniter and burner ports, since carbon and spills block both the spark and the flame path. Dry everything thoroughly. Reseat the burner cap squarely so the ports line up. If the burner lights but the flame dies when you release the knob, that is usually the thermocouple, not something you can clean, and it needs service.
Oven Checks
For an oven that will not hold temperature, first make sure the door closes fully and the seal is intact, because a La Cornue oven relies on a tight cavity. Give the oven a full preheat before judging it, as these heavy ranges take time to come up to temperature. If baking runs consistently hot or cold, do not try to adjust the thermostat yourself; note how far off it is and book a calibration. A flame that will not stay lit in the oven is a valve or thermocouple issue for a technician.
| Symptom | Try First | If It Continues |
|---|---|---|
| Burner will not light | Clean ports, reseat cap | Igniter or thermocouple service |
| Flame dies when knob released | None safe to try | Thermocouple replacement |
| Oven slow to heat | Allow full preheat, check seal | Thermostat or valve diagnosis |
| Oven runs hot or cold | Note the offset, do not adjust | Thermostat calibration |
| Yellow or lifting flame | None safe to try | Altitude combustion tuning |
Where to Stop
Do not adjust orifices, air shutters, or the thermostat yourself, do not work on the gas line, and do not remove burner assemblies. If you smell gas, shut off the supply, ventilate, and call for service. On a La Cornue, cleaning ports and reseating caps is the limit of safe DIY; everything else is a technician's job.
Still Not Right?
Book a diagnosis with a brand-focused technician. Diagnostic and travel fees, if applicable, are confirmed before the appointment and before repair approval.