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

• The defining Bosch gas-oven no-ignite fault is a weakened hot-surface (glow-bar) igniter that still glows but no longer pulls enough current to open the safety valve. Bosch gas ovens use a glow-bar hot-surface system, not the NTC-thermistor / relay-board electric architecture of the brand's electric wall-oven line, so the real pass/fail here is the igniter's amp draw, not whether it glows. On models that display fault codes, a Bosch gas range can throw an E118 — commonly a flame-detection / ignition failure, meaning no stable flame was confirmed after the ignition attempts, which is exactly what a weak glow-bar igniter that can't open the safety valve produces (E118's precise meaning varies by model series; E115 is a separate over-temperature safety cutout, not an ignition fault). The igniter is wired in series with the oven safety valve, and as it ages its resistance climbs until current drops below the valve's open threshold. The published rule of thumb: if the igniter glows more than ~90 seconds without the burner catching, it has weakened and must be replaced even though it still lights up. We clamp-meter igniter current on every Bosch gas-oven no-bake before condemning anything (RepairClinic / AppliancePartsPros 'igniter glows but won't light' guidance).
• Two distinct Bosch oven igniters cover the gas fleet and the part is model-specific. On HGS-series sealed-burner gas ranges (HGS235/236/242/245/246/247/252UC) the bake igniter is 00492431 (AP3674290, PS8722793; supersedes 00487383, 1107469, 20-01-500, 00610098), a 120V silicon-carbide hot-surface igniter rated to a 3.2-3.6A safety valve. On Bosch/Thermador/Gaggenau PRG-class pro ranges the igniter is the nitride unit 00644424 (AP4309945), officially listed by Bosch-home.com and Thermador.com as 'Ignition device IGNITOR HSI, NITRIDE.' We confirm model/serial before ordering because the wrong igniter geometry won't seat at the burner.
• Igniter-type sets the amp spec, and mismatching it is the classic misdiagnosis. Square / carbon-nitride Bosch oven igniters are used with safety valves rated ~3.3-3.6A, with ~3.0A the lowest acceptable reading; round/older-style igniters run lower (down to ~2.2A on valves rated 2.5-3A). An igniter reading under its spec leaves the bimetal in the valve unopened forever even while the bar glows orange. We read the actual current against the igniter type rather than eyeballing the glow, because a glowing-but-under-amperage igniter is exactly the case owners assume is 'fine.'
• When the igniter tests good on current draw (~3.2A+) but no flame appears, the fault shifts to the oven safety valve, the Bosch dual gas valve 00415497 (AP2832926), which feeds BOTH the bake and broil burners on Bosch/Thermador/Gaggenau gas ovens. The valve is a fail-safe bimetal device that only opens once the igniter heats it; a tired or snapped bimetal (common after ~5 years of cycling) stays shut regardless of a healthy igniter. We meter the valve — a good coil reads only a couple of ohms across the terminals, OL means it's open and dead — and we replace the valve ONLY after the igniter passes its amp test, so an owner isn't sold a $150-plus valve when a weak igniter is the real cost.
• A single surface burner that clicks but never lights (neighbours fine) is usually that position's igniter switch behind the knob, not the oven igniter or the shared module. The Bosch surface burner igniter switch 00428049 (AP3842359; 5A 125-250VAC; supersedes 00189885, 00413944, 00415094, 00421651, 1094738) sends spark voltage when the knob is turned; a spill or boil-over fouls or sticks it so that one position goes dead (or sparks even in OFF). We meter the suspect switch for continuity in OFF — continuity present in OFF means it's shorted and replaced — and on some Bosch ranges the potentiometer 00422748 is paired with the switch for a single-burner spark fault.
• Every surface burner clicking but none lighting (or constant clicking) points at the shared spark/re-ignition module — Bosch range spark module 00631765 (or the 6-point re-ignition module 00753257 on later platforms, 00619017 re-ignition variant), which fires every surface electrode. Before condemning the module we rule out the $0 causes that mimic it: a wet or grease-fouled burner cap, clogged ignition ports, or a spark electrode 00631633 (AP5950372, PS10057850; supersedes 4162041) cracked at its ceramic so the spark jumps to the burner base instead of the cap gap and the gas never lights. We dry and reseat the cap, clear ports, and check electrode ceramic before naming the module.
• Two free, non-part fixes we rule in first on a Bosch gas 'won't ignite' call: gas-supply and ignition-path basics. A closed or partly-closed manual gas shutoff, a recently emptied LP tank, or air in the line after a gas-off leaves a healthy igniter glowing with nothing to burn; and a burner that's been through a boil-over needs its head dried and ports cleared before the spark can find gas. We verify gas is actually reaching the burner and that the cap/ports are clean and dry before quoting any igniter, valve, switch or module — and all gas-valve, orifice and NG/LP conversion work on these ranges is TSSA-certified gas-fitter scope in Ontario.

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

• The recurring Bosch gas-oven pattern we see in Toronto is the classic glow-but-no-flame: the igniter lights up orange, the owner watches it glow for a minute-plus, and the burner never catches — almost always a weakened hot-surface igniter that's dropped below the amp threshold to open the safety valve, not the dead 'no glow at all' case. On code-displaying models this is the condition that surfaces as an E118 flame-detection/ignition fault. The second recurring pattern is the single surface burner that clicks but won't light after a spill, which traces to a fouled behind-knob igniter switch rather than the oven igniter. We clamp-meter igniter current before condemning the valve so owners aren't sold a $150-plus gas valve when the cheaper igniter is the real fault.
• We bring the Bosch bake igniter 00492431 (AP3674290, PS8722793) for HGS ranges and the nitride 00644424 for PRG pro ranges, plus the surface burner igniter switch 00428049, a spark electrode 00631633, the spark module (00631765/00753257), and a clamp meter to read igniter amps on site. The dual gas valve 00415497 is staged and fitted only after the igniter passes its current test, and any gas-valve or LP/NG work is done under TSSA gas-fitter scope.

For the full Bosch wall oven module — every fault, part number and code — see Bosch 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.