David Carter Key Takeaways
- Star Burner ports clog more easily than standard round burner ports because the five-point geometry has more narrow channels.
- A wet igniter from a boilover will click continuously without lighting — drying the igniter with a hair dryer often resolves it immediately.
- A weak or cracked igniter spark module is the most common part failure behind persistent no-ignition on Pro Grand and Pro Harmony ranges.
- Gas supply issues — a partially closed valve or low pressure — can cause intermittent ignition failure across all burners simultaneously.
- Electronic igniter faults on Thermador ranges may trigger error codes on dual-fuel models with a digital display.
The Bottom Line
Most Thermador Star Burner ignition failures are caused by clogged ports or a moisture-soaked igniter — both of which owners can address themselves. If the burner still won't light after cleaning and drying, the spark module likely needs professional replacement.
Thermador Range Burner Not Igniting: Understanding Star Burner Failures
When a Thermador range burner not igniting problem appears on a Pro Grand or Pro Harmony range, the distinctive five-point Star Burner design is often both the reason and the solution. Star Burners deliver a wider flame pattern that heats cookware more evenly than a standard circular burner — but the five-point geometry also creates more narrow ports that can clog, and more igniter electrodes that can be affected by spills.
Clogged Burner Ports: The Most Common Cause
Each Star Burner point contains small gas ports that must remain clear for an even flame. When cooking residue, boilover liquid, or grease enters these ports, the gas flow becomes uneven or blocked. The igniter sparks but the gas cannot exit cleanly, resulting in no ignition or a weak, partial flame. Removing the burner cap and cleaning the ports with a small-gauge wire, toothpick, or dedicated burner cleaning tool resolves this in minutes. Do not use a toothpick tip that can break off inside a port.
Moisture is the other leading cause of ignition failure on Star Burners. A boilover soaks the porcelain igniter tip, causing the spark module to click continuously without producing a spark strong enough to light gas. Removing the burner cap and grate and allowing the igniter to dry — or accelerating the process with a hair dryer on a low heat setting — usually restores normal ignition within thirty minutes. Do not use the range while the igniter is still wet.
| Symptom | Likely Cause | Applies To | Owner Fix? |
|---|---|---|---|
| One burner clicks but won't light | Clogged ports or wet igniter | Pro Grand, Pro Harmony | Yes — clean ports, dry igniter |
| All burners clicking constantly | Moisture on control panel | All Star Burner models | Yes — dry thoroughly |
| Weak spark, partial ignition | Worn spark module electrode | Pro Grand, Pro Harmony | No — electrode replacement |
| No spark sound at all | Failed igniter switch or module | All models | No — igniter module service |
| All burners intermittently fail | Gas supply issue or low pressure | All models | No — gas line inspection |
Pro Grand vs. Pro Harmony: Any Differences?
The Pro Grand range features the ExtraLow simmer feature that opens a secondary gas valve for ultra-low simmer temperatures — a system that has its own dedicated burner port assembly distinct from the main Star Burner ports. If your Pro Grand range ignites normally on high but the ExtraLow simmer function fails to hold a flame, the ExtraLow valve or its secondary port may need separate service. Pro Harmony ranges do not include the ExtraLow dual-valve system, making their ignition circuit slightly simpler to diagnose.
When to Call a Professional
If cleaning the ports and drying the igniter does not restore ignition, the spark module electrode or the igniter switch behind the front panel likely needs replacement. These repairs involve disassembly of the burner deck and, on dual-fuel Pro Grand models, proximity to the electrical supply for the oven circuit. Our Thermador range repair technicians are familiar with both the Star Burner spark module and the ExtraLow secondary valve and can service either in one visit.