Thermador Range Burner Not Lighting: Gas & Induction Troubleshooting Guide

Common Symptoms

• Gas burner clicks repeatedly but flame never ignites
• One specific burner won't spark at all — no click, no glow, no flame
• Burner ignites but flame lifts off or extinguishes immediately after releasing the knob
• Induction zone shows an error code (F-series) or does not respond to cookware
• All gas burners click at once when only one knob is turned (spark module issue)

Most Likely Causes

1. 1

   Contaminated or Misaligned Burner Cap (Gas — Most Common, Easiest Fix)

   The single most common cause of a gas burner failing to ignite is a displaced or food-contaminated burner cap. After boilover spills, the burner cap can shift off-center, blocking the gas ports and preventing the flame from catching even when the spark is working. Lift the burner cap, clean the gas ports with a pin or paper clip, dry completely, and reseat the cap flat and centered. Many 'burner won't light' service calls are resolved with a 5-minute cap cleaning — always start here before testing electrical components.

2. 2

   Weak or Failed Spark Electrode (Gas Models)

   Each Thermador gas burner has a ceramic spark electrode — a white ceramic insulator with a metal tip positioned 3–4mm from the burner cap. The electrode produces the spark that ignites the gas-air mixture. A cracked ceramic insulator shorts the high-voltage spark to ground instead of arcing to the burner cap, preventing ignition. Visual inspection reveals hairline cracks, carbon tracking on the ceramic, or a bent/corroded tip. The electrode winding resistance spec for Thermador sealed burner electrodes is 0–1,500Ω — an OL (open) reading means the electrode wire has broken. Individual Thermador spark electrodes cost $25–$55 depending on the model.

3. 3

   Failed Spark Module (Gas Models — Affects Multiple Burners)

   The spark module is a centralized ignition control box mounted inside the range that receives the ignition signal from each burner knob and distributes high-voltage pulses to all electrodes. When the spark module fails, burners typically stop sparking entirely — pressing any burner knob produces no click sound. Alternatively, a partially failed module may cause all burners to spark simultaneously when only one knob is pushed (a classic spark module symptom). Thermador uses BSH platform spark modules — replacement costs $60–$120. Test the module by checking for 120V AC at the module input during a burner push; if voltage is present but no spark output appears at the electrode wire, the module is faulty.

4. 4

   Gas Supply Issue or Flame Lifting (Gas Models)

   If the burner ignites briefly then extinguishes when the knob is released, the thermocoupling flame sensor (on models with flame failure detection) is not reaching operating temperature fast enough to hold the gas valve open. Causes include low gas supply pressure, a partially blocked burner port preventing full flame establishment, or a failed thermocouple/thermopile on models equipped with one. Check that the gas shutoff valve behind the range is fully open. On dual-fuel models (PRD304), verify the gas supply line is not partially crimped during installation.

5. 5

   Induction Zone Fault (Induction Models — PRCS304, PRD304)

   Thermador induction ranges display zone-specific fault codes when an induction coil or inverter board circuit fails. Common codes include F-07 (coil overheat), F-12 (induction coil open), and F-23 (inverter board fault). An induction coil that has failed open will test OL in resistance mode (healthy coil: typically 0.5–5Ω depending on coil diameter and layer count). Induction zone problems not caused by incompatible cookware (non-ferrous pans will not couple) are almost always the coil assembly or the inverter board — both require disassembly of the cooktop surface and are advanced repairs.

Quick DIY Checks

1. 1GAS SAFETY FIRST — Before inspecting any burner component on a Thermador gas range (PRGS304, PRD304, PRDS366W), turn off the gas supply valve located behind or below the range. Also unplug the range from the 120V wall outlet to prevent the spark module from operating while you work near electrodes. After turning off the gas, wait 5 minutes for any residual gas in the supply line to dissipate before working near the burner assembly. If you smell gas that does not dissipate within 5 minutes of shutting the valve, evacuate and call your gas utility — do not continue repairs.
2. 2CLEAN AND RESEAT THE BURNER CAP — Remove the burner grate over the affected burner. Lift the burner cap straight up — it simply rests on the burner base with no fasteners. Inspect the underside of the cap for food residue, grease, or debris packed into the gas port holes around the perimeter. Use a straightened paper clip or sewing pin to clear each gas port individually. Clean the burner cap and base with a damp cloth. Dry completely (wet ports prevent ignition). Reseat the cap flat and centered — a slight tilt is enough to prevent ignition. Restore gas and power, then test. This resolves the issue in approximately 40% of no-light calls.
3. 3INSPECT THE SPARK ELECTRODE — With the burner cap removed, locate the spark electrode — a white ceramic cylinder approximately 1 inch tall, positioned next to the burner base. Examine the ceramic body under bright light for hairline cracks, carbon tracking (black streaks on the ceramic), or corrosion on the metal tip. The electrode tip should be intact and positioned 3–4mm from the burner body. A cracked or carbon-tracked ceramic must be replaced — the crack allows spark energy to short to ground instead of jumping to the burner. Visually damaged electrodes account for roughly 35% of no-spark failures on Thermador ranges.

Repair vs Replace

Recommended Tools & Parts

• Thermador Gas Range Spark Electrode (Sealed Burner)

  Replacement spark electrode for Thermador gas sealed burner ranges (PRGS304, PRDS366W, PRD304). Fixes no-spark on an individual burner when ceramic is cracked or tip is corroded. Winding resistance spec: 0–1,500Ω. Verify by model number. Amazon tag: fixitfastai-20.

  $25–$55

  Buy on Amazon →

• Thermador Range Spark Module / Ignition Module

  Replacement spark ignition module for Thermador gas ranges. Fixes all-burners-dead or all-burners-click-together symptoms. BSH platform part — verify compatibility with full model number. Amazon tag: fixitfastai-20.

  $60–$120

  Buy on Amazon →

• Digital Multimeter

  Required for electrode winding resistance test (0–1,500Ω spec) and induction coil resistance test (0.5–5Ω spec). Non-contact voltage tester function also useful for verifying spark module input power.

  $20–$45

  Buy on Amazon →

Links are Amazon affiliate links (tag: fixitfastai-20). Prices are estimates.

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