Gas cooktop burner goes out when the knob is released, even though it lights initially.

Safety: Work with gas components only if you are competent. Turn off the gas supply before removing parts.

• Hold knob longer: When lighting, press and hold the knob for 5–10 seconds to allow the thermocouple to heat. If the flame still goes out, continue with the steps below.
• Check flame position: Ensure the burner cap is correctly seated so that the flame contacts the thermocouple tip.
• Clean thermocouple: Gently clean the thermocouple tip with fine emery cloth to remove oxidation.
• Replace thermocouple: If the problem persists on one burner, replace that burner’s thermocouple with the correct Ariston part, routing it back to the gas valve as originally installed.
• Gas valve: If multiple burners on the same manifold have this issue, the gas safety valve may be faulty and should be replaced by a licensed gas technician.