Thermador Gas Stove Burner Won't Turn Off: Causes

Shut the burner down#

First make sure it is a real fault and not a knob turned only part way — press in and rotate fully to the off stop. If the flame still burns, close the shutoff valve behind the range a quarter turn so the handle sits across the pipe, which cuts gas to the whole cooktop. Never leave a burner you cannot control running unattended.

Why a Thermador burner won't go off#

• A worn valve stem. Thermador's sealed burners meter gas through a valve behind each knob. As the internal seat wears, it stops closing fully, leaving a small flame or a hiss even at off.
• A stripped or cracked knob. If the knob's D-shaped socket rounds out, turning it no longer turns the valve all the way. The flame looks like it should be off while the valve stays cracked open.
• A misaligned stem or bent shaft. A knock or a botched cleaning can leave the stem out of line so it never reaches the closed position.
• Debris in the valve. Grease drawn into the valve body over years can hold it slightly open.

What you can and cannot DIY#

Swapping a rounded-out knob is a fair homeowner job, and it is worth ruling out first because it is cheap and common. Anything inside the valve body — a worn seat, a stuck stem, debris in the port — means opening the gas manifold, which is a technician repair on a sealed-burner Thermador. Do not tape or lubricate a leaking valve to buy time.

Before the holiday cooking season#

A burner that will not switch off is not something to nurse through a busy cooking week. If yours needs an extra shove to go out, have the knob or valve sorted now, while you can cook safely on the others. If a firm turn to off does not kill the flame, book a visit and a technician will replace the knob or the burner valve.