Thermador · Troubleshooting
Thermador Burner Clicking or Not Lighting
Some clicking on a Thermador is by design: Star burners relight themselves and the ExtraLow burners cycle on low. Clicking with the knobs off, or sparking that never stops, is usually a wet valve switch, a cap off its seat, a dirty electrode or a grounding fault.
$79 service call, applied to the repair. Monday to Saturday, 8 AM to 7 PM.
In short: if you smell gas with the knobs off, leave the house and call from outside. An ExtraLow burner clicking about once a minute on its lowest setting is normal. Clicking with every knob off is most often a wet valve switch that dries out on its own; the checks below show how. Sparks with no flame point at the cap, the ports or the gas supply.
Clicking that is normal on a Thermador
Thermador Pro ranges, rangetops and gas cooktops use the Star burner, with a spark electrode at the base of each one.
- Automatic re-ignition. If a boil-over or a draft puts a flame out, that burner sparks on its own until it relights.
- ExtraLow cycling. Burners with an XLO mark on the knob, on many Pro ranges the left front and left rear, cycle the flame on low. At the lowest XLO mark it comes on for a few seconds and rests for the rest of each minute, with a soft click each time; between SIM and XLO the timing changes with the knob.
- A few seconds to light. With the knob pushed in and turned to HI, a healthy burner catches in about four seconds.
Match the clicking to the cause
| What you notice | What it usually points to | First step |
|---|---|---|
| A burner on XLO clicks about once a minute | ExtraLow cycling, normal | Nothing; turn it up past SIM if it bothers you |
| Clicking with every knob off | Water in a valve switch, or a switch worn closed | Dry it out (step 2 below) |
| One burner sparks but will not light | Cap off its seat, blocked ports, dirty electrode | Clean, dry and reseat the cap |
| Every burner sparks, none lights | Gas off, or air in the line after gas work | Check other gas appliances, then call |
| Burner lights but keeps sparking | Flame missing the electrode, or an outlet ground fault | Reseat the cap; if it persists, call |
Safe checks before you call
- Use your nose first. A faint smell while a burner lights is normal. A steady smell with the knobs off is not: no light switches, no phone inside, leave and call the gas company or 911 from outside.
- Dry it out. After a boil-over or a wet cleaning, switch the range off at the breaker, lift off the grates and caps, and leave it open to the air for a full day.
- Seat and clean the caps. Only the cap lifts off; the brass base is fastened and wired. Wash caps in warm soapy water, dry the ports fully, and set each back flat and centered. Keep sprays and scouring pads off the white ceramic electrode.
- Swap caps to test. Trade the cap of a bad burner with one from a working burner of the same size. If the fault moves with the cap, the cap is clogged or warped. If it stays, the cause is below.
- After gas work. If the gas was off for a remodel or a meter change and a burner will not light after two short tries, turn every knob off, air the room for five minutes and call us or the installer.
What it usually turns out to be
Valve switch wet or worn
What it usually is: on Pro Grand and Pro Harmony ranges each standard burner valve, all but the ExtraLow ones, carries a small switch that starts the sparks when the knob turns. Spilled liquid makes a switch conduct as if its knob were on, so one or more burners keep clicking at OFF until it dries. With age a switch can also stick closed when dry, or stop closing and leave one burner without a spark.
What you can check: whether it began after a spill, and whether nudging one knob near OFF changes the clicking.
What we do: find the switch that misbehaves and replace it, with the gas shut at the wall, then leak test every fitting we opened.
Star cap off its seat, or ports blocked
What it usually is: the flame should burn at the ports along every point of the star. Burned sugar or pasta starch in the ports nearest the electrode keeps gas from the spark, and a cap slightly off center gives a lopsided flame.
What you can check: the flame. It should be even all the way around the star, with no gaps.
What we do: clean the ports, check the cap for warping, and check that the burner sits square on its base; when it is out of line the flame roars or shows gaps.
Electrode cracked, crusted or loose
What it usually is: a ceramic plug in the brass base, wired from below. A pot set down hard cracks it, baked grease weakens the spark, and a disturbed wire can sit loose.
What you can check: the cool ceramic for a crack, a chip or a black crust.
What we do: clean or replace the electrode, lock its wire in place, and confirm the sparking stops the moment the burner lights.
The ExtraLow system
What it usually is: each XLO burner uses a solenoid on its gas, a simmer potentiometer behind the knob and a simmer board that times the cycles. When one fails, the burner clicks without lighting at XLO, never cycles, or goes out on low and stays out.
What you can check: whether it misbehaves only between SIM and XLO while working normally from HI to SIM.
What we do: test the potentiometer, the solenoid and the board, in that order, and order a board only when it fails; it often takes the blame for the other two. On older Professional Series ranges and all-gas cooktops, replacing an original potentiometer means replacing all of them and using the matching simmer board, often as a kit; we say so before ordering.
Spark module or outlet ground
What it usually is: the module under the cooktop fires the electrodes and senses each flame; a failing one sparks weakly, not at all, or without end. Flame sensing also needs a good ground and correct polarity at the outlet; a fault there often shows up as constant sparking after a remodel.
What you can check: how many burners are affected, and whether it began after electrical work. Never use a plug adapter.
What we do: rule out switches and electrodes, then test the module and the outlet. House wiring faults need an electrician; we show you the readings.
Gas supply or the wrong gas setup
What it usually is: a shutoff left partly closed, low supply pressure, or a range set for the wrong gas. Sparks sound normal, but flames light late, burn tall and yellow, or blow out on low.
What you can check: whether other gas appliances work normally. Leave the shutoff and the line behind the range alone.
What we do: measure pressure, match orifices and low-flame settings to the gas type, and leak test what we touch. Gas conversions are a technician job.
Ranges, rangetops and cooktops
- Pro Grand and Pro Harmony ranges. All-gas and dual fuel models share the same top. See Thermador range repair.
- Grill and griddle. The Pro Grand grill lights with a glowing igniter, not a spark, so it does not click; the griddle is electric. Neither works in a power outage.
- Rangetops, cooktops and older Professional Series. The same burners and re-ignition. See cooktop repair.
- The oven. A separate system; see Thermador oven not heating.
Stay safe. Keep fingers off a sparking burner. If one sparks for more than a few seconds without lighting, turn it off and let the gas clear for a few minutes before one more try. If the power fails while cooking, turn every knob off and air the room for five minutes. Never remove the control panel or move the range on its gas line.
What the repair costs
On a clicking or dead burner the repair is usually a spark switch, an igniter, the spark module or a valve; the rows below cover each. The $79 visit goes toward the repair once you approve the written price.
Professional range and rangetop repair (Wolf, Viking, Thermador, Monogram, Dacor)
| Repair | Typical price, parts and labor |
|---|---|
| Burner igniter or spark switch | $250 to $450 |
| Spark module | $300 to $600 |
| Burner valve | $350 to $650 |
| Gas oven igniter | $300 to $550 |
| Gas oven safety valve | $400 to $800 |
| Bake or broil element (dual fuel) | $350 to $700 |
| Oven temperature probe | $250 to $450 |
| Convection fan motor | $400 to $750 |
| Door hinges, pair | $350 to $650 |
| Oven door gasket | $250 to $450 |
| Electronic control or relay board | $650 to $1,500 |
Typical Orange County ranges for parts and labor. The $79 service call is applied to any of them. Parts that ship from the manufacturer and older or discontinued models can run higher. You get the exact written price after the diagnosis and before any work starts.
Thermador ignition parts usually arrive from a distributor in a few business days; you hear the lead time first. See pricing, professional range repair and Thermador repair, or book a visit.
Talk to the technician first
Monday to Saturday, 8 AM to 7 PM. The $79 service call is applied to the repair.
Thermador burner clicking: questions
Why does my Thermador range keep clicking with all the knobs off?
A valve switch is closed when it should be open, usually because it got wet. Breaker off, caps off, a day to dry. If it returns when dry, the switch is worn.
Is it normal for a Thermador burner to click on the lowest setting?
Yes, on any burner whose knob has an XLO mark; on many Pro ranges that is the left front and left rear. On the lowest settings the flame cycles on and off about once a minute, with a soft click each time. A burner without XLO should be silent once lit.
Why does my Thermador burner keep sparking after it lights?
The module does not see the flame. Usually the cap is off center or the electrode dirty; otherwise the wire, the module or the outlet ground.
Why will one Thermador burner not light when the others do?
Its cap, ports, electrode or valve switch. Swap caps with a working burner of the same size; if the fault stays put, call.
Why are my Thermador flames yellow?
On natural gas they should be blue; yellow means a cap not seated, clogged ports or the wrong gas setup. On propane, slight yellow tips are normal.
Can I light a Thermador burner with a match in a power outage?
Turn every knob off and air the room for five minutes first. Light a standard burner by hand only as your use and care guide describes; Thermador says not to light the ExtraLow burners by hand, and the griddle and grill need power.
Are you Thermador factory service?
No. We are an independent service, not affiliated with Thermador, repairing Thermador ranges and cooktops across Orange County from Irvine, Monday to Saturday, 8 AM to 7 PM.