Thermador Wall Oven Repair in Toronto — Gas oven won't ignite (igniter glows weakly)

• Weak glow-bar igniter is the signature gas-won't-ignite fault on Thermador (BSH) gas ovens. The bake igniter draws current in series THROUGH the oven safety valve's bimetal to open it; as the carborundum element ages it still glows but no longer pulls enough amperage to crack the valve, so the burner never lights. The diagnostic rule is concrete: if the igniter glows more than ~90 seconds with no flame, it is too weak regardless of how bright it looks. We clamp-meter the draw before condemning anything — the OEM bake igniter 00492431 (replaces 00487383 / AP3674290 / 20-01-500 / 610098 / 1107469) is a 120V unit specifically rated to fire 3.2-3.6 amp safety valves, so a reading under spec confirms the igniter, not the valve.
• Older Thermador/Bosch gas cavities use glow igniter 00487242 (replaces 1014017 / 15-10-136 / 35-00-189 / 00488049 / 00491375 / PS8720933) and the related glow-bar 00415504. These are a different physical igniter than the 00492431, so model-tag confirmation comes first — ordering the wrong glow bar is the most common parts misfire on these calls. A correctly matched igniter that reads open on continuity, or that glows but won't open the valve on amp draw, is the replacement.
• Igniter glows but no gas at all: because Thermador safety valves rarely fail, when a known-good igniter is drawing in the 3.2-3.6A band and the valve still won't pass gas, the fault moves to the safety valve / gas path rather than another igniter. The honest sequence is to confirm igniter amp draw is in-spec FIRST, then test the valve and verify the supply line and manual shutoff are fully open before condemning the (expensive, rarely-needed) safety valve assembly — many 'won't ignite' calls are actually a partially-closed supply valve after a kitchen reno.
• E115 on Thermador (BSH) ovens means 'upper oven temperature too high' — an overheat/over-temperature fault, NOT a flame-failure or igniter code. It is triggered either by a stuck/defective relay on the electronic oven control board (a genuine overheat) or by a faulty oven temperature sensor / wire-harness giving a false high reading. On a gas won't-ignite call E115 would be incidental, so rather than blaming the igniter or gas valve we confirm sensor resistance (~1080 ohms at 70F) and the control-board relay. (Thermador's flame/probe-side codes E116/E122/E123 are separate meat-probe faults, also not ignition codes.)
• Convection/broil ignition is a separate gas path from bake on fan-equipped Pro and Masterpiece gas cavities — each burner has its own igniter and the broil igniter can read a low standby current that is actually normal. An oven that bakes but won't light on broil (or vice-versa) points at that circuit's specific igniter, so we verify each heat path independently rather than swapping the bake igniter for a broil-side no-light.
• Crack-and-contaminate failures: glow-bar igniters are brittle carborundum/silicon-carbide and fail from hairline cracks and from oily-finger handling that creates hot spots — touching the gray element during a prior DIY install is a documented way to kill a new 00492431. On Toronto re-do calls we frequently find a recently-installed aftermarket igniter already failed for exactly this reason, so we handle the new element by its ceramic base only and re-verify amp draw after install.
• Spark-ignition note for Pro ranges: the Star burner COOKTOP uses a spark module and electrode (the clicking complaint), which is a different ignition system than the oven's glow-bar bake igniter. A 'won't ignite' complaint has to be pinned to oven vs. rangetop first, because the oven cavity is glow-bar/safety-valve and the surface burners are spark-path — conflating the two sends the wrong part to the call.

Thermador gas oven won't ignite (igniter glows weakly) in Toronto — the local specifics

• The recurring Thermador won't-ignite pattern we see in Toronto is the glow-bar igniter that still lights up orange but no longer opens the safety valve — homeowners assume the valve or board failed because the igniter is visibly glowing, when an amp-draw test shows it has drifted under the 3.2-3.6A spec. The second recurring pattern is a failed aftermarket igniter from a prior DIY swap, killed by being handled on the gray element, and the occasional 'won't ignite after a kitchen reno' that traces back to a partially-closed gas supply valve rather than any part at all.
• We bring the matching Thermador/Bosch glow-bar bake igniters (00492431 and 00487242 families, plus 00415504) to these calls along with a clamp meter to confirm amp draw before replacing anything, so the in-spec valve and control board aren't condemned unnecessarily. If draw is good and the valve still won't pass gas, the safety valve / gas-valve assembly is then ordered model-specific through the BSH channel.

For the full Thermador wall oven module — every fault, part number and code — see Thermador wall oven repair in Toronto, and for the same fault across all brands the wall oven gas oven won't ignite (igniter glows weakly) guide.