Bosch Stove Repair in Toronto — Knob not turning or igniting

• The first split on every "knob not working" Bosch call is whether the KNOB is broken or what sits BEHIND it has failed, because the cook reports both the same way. A knob that spins freely, slips, or no longer clicks into detents has usually cracked or stripped its D-shaped bore from heat-cycling, and the genuine fix is the surface-burner control knob 00632515 (cooktop; AP5809104, supersedes 4162117 / PS9495599) on glass-top/slide-in builds, the gas cooktop burner knob set 00654043 (2693353 / AP5325796 / PS8731489) on NGM-family ranges (NGM8054/8654UC), or the oven selector knob 00418117 on the oven function dial. We pull the knob and turn the bare stem first: if the stem actuates the valve/switch normally, it is purely a knob swap, not a parts-throw at the electronics underneath.
• On a Bosch GAS top, a knob you can turn but the burner never lights at LITE is the per-burner spark ignition switch behind that knob, not the knob: Bosch 00189008 (PS8698334; replaces AP2821597 / 00411414 / 1028579 / 14-33-936). The switch is only supposed to feed the spark module when the knob reaches the LITE detent; a switch worn, or fouled by a boil-over, won't pass voltage so that one burner clicks weakly or not at all while its neighbours light. Conversely, a switch with contacts bridged closed by a spill makes the top spark with every knob OFF. We dry and meter that switch through the knob's LITE travel before condemning it, since it is the cheapest fix in this chain.
• A gas knob that physically won't turn, or won't return to OFF, with the burner stuck on is the surface-burner gas valve itself seized behind the knob — Bosch 00411253 (AP2828839 / PS8707103; also fits Thermador/Gaggenau). Bosch's documented test is to pull the knob and try to rotate the bare valve stem by hand: if the stem won't move or the burner stays lit at the OFF position, the valve is defective and gets replaced. We never force a seized stem on a gas job — forcing it risks cracking the valve body into a leak — so a no-rotate stem is a TSSA-gated valve replacement, not a knob.
• On a RADIANT electric glass-top (HEI/HES-prefix 800-series), a knob that turns but the zone never powers — or never comes down from high — is the surface-element control / infinite switch behind it, not the knob: Bosch 00422133 (PS8713176 / AP3723298; supersedes 1050277 / 422133) or the companion surface-element control switch 00632570. The switch is what the knob shaft actuates to feed line voltage and set the element's duty cycle; a worn or arced contact set passes nothing, so the element tests good on the bench but never sees power on the range. We meter continuity across the switch terminals through the knob's full rotation before condemning it — it is a fraction of a board's cost.
• A very common false "knob not working" is the knob slipping on a stem that is itself fine: the D-flat inside the knob bore has rounded out from years of heat and torque, so the knob spins without driving the valve or infinite-switch shaft to its setpoint. This reads identically to a dead valve/switch from the front, but pulling the knob and turning the bare stem with pliers proves the shaft still indexes normally. The cure is the matching OEM knob (00632515 / 00654043 / 00418117) confirmed against the model tag, NOT the part behind it — replacing a $300 valve or board for a $20 rounded-out knob is the classic misdiagnosis here.
• An induction (HII-prefix range / NIT-prefix cooktop) Bosch has NO mechanical knobs at all — it is a touch-slider deck — so a "knob" complaint on an induction build is really an unresponsive touch zone. A flashing lowercase 'e' or an E011 control-panel / touch-key fault means a wet panel or something resting on the glass is holding a key pressed; Bosch's first step is to wipe the glass dry, then kill the breaker for ~5 minutes and restore power. An E005 (communication fault between the user-interface and main control board, across the UI-to-main ribbon cable) clears on the same breaker reset on the transient ones. We confirm by model tag that there are no physical knobs before chasing any part, and an 'e'/E011/E005 that clears on a wipe-and-reset is a no-part repair, not a control board (00745798 / 00748595).
• When the same knob position behaves differently on bake vs the cooktop, the fault can be a heat-degraded terminal or shaft index rather than a dead control: heat-cycling oxidizes a marginal crimp at the infinite-switch tab (00422133 / 00632570) or the spark-switch lead (00189008) until the knob's signal intermittently fails to register under load. We inspect and re-terminate the receptacle and switch tabs before throwing a knob, a switch, or a board at it — this is the intermittent "knob works sometimes" that vanishes on the bench and gets misdiagnosed as a recurring bad part.

Bosch knob not turning or igniting in Toronto — the local specifics

• The recurring Bosch knob pattern we see across Toronto is the cracked-or-rounded-out knob that spins freely — heat-cycling splits the D-bore on the surface-burner and oven knobs — which homeowners read as a dead burner or dead oven until we pull the knob and prove the bare stem still indexes. On gas builds the second-most-common is the LITE-position spark switch (00189008) fouled by a boil-over so one knob clicks weakly or not at all; the genuine seized gas valve (00411253) is the less-common but most-serious version, and on radiant glass-tops it is the infinite switch behind the knob, not the knob, that has failed.
• We bring the Bosch knob and behind-knob switch stock to these Toronto calls — 00632515 surface-burner knob, 00654043 NGM gas-knob set, 00418117 oven selector knob, 00189008 spark ignition switch, and the 00422133 / 00632570 infinite/surface-element switches — and decode the model tag on site so the right knob bore and the right switch go on the first visit. The seized surface-burner valve 00411253 is ordered by model when a no-rotate stem confirms it.

For the full Bosch stove module — every fault, part number and code — see Bosch stove repair in Toronto, and for the same fault across all brands the stove knob not turning or igniting guide.