When a Thermador burner won’t light, the cause is usually something you can see from above: a burner cap that is not sitting flat on its base, a crown or igniter that is still damp from cleaning, or a port blocked with boiled-over food. If you can hear the igniter clicking but no flame appears, start there. If you smell gas at any point, stop at once: do not turn anything on or off, do not light anything, leave the house and call the gas utility or 911 from outside. Everything on the gas side beyond the cap and crown belongs to a technician.
Why won’t my Thermador burner light?
Start with how it fails. A burner that clicks but does not light has working electrical ignition and a gas path that is blocked, wet or misaligned. A burner that does not click at all points at the power or the ignition side. A burner that lights for a moment and goes out, or that burns unevenly, usually has a part sitting wrong or ports that are partly blocked. Our Star Burner pages are the source for the checks below, and the Star Burner guide shows the parts.
The gas cooktops on our site include the 30-inch SGS305TS, the 36-inch SGS365TS and SGSX365TS, the SGSX365CS with a center wok burner and the Professional SGSP365TS, all described with Star Burners.
Is the burner cap seated flat?
This is the first check, and it fixes more burners than any other. Our cooktop troubleshooting page says to check that the burner cap is seated flush on the burner base, because the star shape must align with the gas distribution ring. Lift the cap off, look at the base, and set the cap back so it sits flat without rocking. Star burner caps differ between burner sizes on the same cooktop, so make sure the cap on each burner is the one that belongs to it, especially if you took them off for cleaning.
Do this only when every burner is off and the cooktop is cool. Never light a burner with the cap off. If a burner is turned on but does not light, turn its knob back to off and let the kitchen air out before you try again; if you notice a gas smell at any point, use the steps at the top of this guide.
Could dampness be the cause?
Yes, and it is common after cleaning. Our StarSpeed burner guide says a crown refitted damp is the single most common cause of a burner that clicks and will not light, because the spark tracks across the moisture instead of jumping to the gas. Our cooktop troubleshooting page also says to dry the igniter if it was recently cleaned. Leave the parts to air dry fully, wipe the base with a dry cloth and try again later.
If you have just washed the grates and caps, our guide on how to clean Thermador range grates explains how to put everything back, and the habit of drying parts completely is the same.
Are the ports blocked?
A Star burner spreads its ports along the arms of a star, so a port blocked at one point can disturb the flame. Our guides describe clearing blocked ports gently, and they stress not to widen the ports. Because the guides give different tool advice, follow your owner’s manual for how to clear ports on your model, and stop if you are unsure. See the Star Burner guide for the parts and the care.
A burner that lights but burns yellow, tall or lazy is a different symptom, covered in our yellow flame guide. A burner that lights but no longer surges on high is covered in our StarSpeed problems guide.
What if every burner will not light?
Then the burner parts are not the problem. Our StarSpeed guide says that if every burner behaves the same way, you should stop looking at burners, because the pattern points at the supply: a partly closed shutoff, a regulator problem or a cooktop set up for the wrong gas. It adds that a range set up for natural gas running on propane, or the reverse, without the correct orifices needs the correct conversion kit and a qualified technician.
Do not adjust a valve, a regulator or any gas part yourself. Tell the technician what you saw: which burners fail, whether you hear clicking, whether anything changed recently such as cleaning, a move or work on the gas line.
What if there is no clicking at all?
A gas cooktop still needs electricity for the igniter. If there is no click on any burner, check that the kitchen circuit has power, for example that other appliances on it work and the breaker has not tripped. If the cooktop has touch controls and they are unresponsive, our cooktop troubleshooting page advises cleaning the control area with a dry cloth, making sure nothing is resting on it and cycling power at the breaker. If it is still silent, the ignition or control side needs a technician. Do not open the cooktop.
Never use a match or a lighter as a workaround. A burner that will not spark needs its ignition fixed, and lighting a burner by hand with the grates off or the cap out of place is how a small problem turns into a burn.
When should you call a technician?
Call if the burner still will not light after you have checked the cap, dried the parts and cleared the area, if only some burners work in a pattern, if every burner fails, if you hear no clicking or if the flame is unsafe. We are an independent repair company, not the manufacturer. Thermador cooktop repair starts with a diagnostic visit, and we confirm the estimate before any work begins. Replacing an igniter or a spark module is usually far cheaper than replacing a cooktop, but the gas side is always a technician’s job.
