Thermador Stove Repair in Toronto — Knob not turning or igniting

• On a Thermador Star-burner gas range the most common "knob does nothing" fault is a failed spark/ignition switch on the valve shaft behind the knob -- you hear (or don't hear) clicking but the burner won't light, or the burner sparks only on "Lite" then quits. The part is the behind-knob igniter switch 00189008 (BSH/Bosch, replaces 00411414 / 1028579 / 14-33-936 / 189008; PS8698334), which clips onto the valve stem and signals the spark module when the knob hits the Lite detent. We pop the knob, pull the metal retaining clip, and meter the switch before condemning the igniter or spark module -- a dead switch makes a perfectly good star burner act like the whole knob is broken.
• A knob that physically won't rotate (or rotates with no resistance/spongy feel) on a Thermador surface burner is a seized or stripped gas valve, not the knob plastic. Thermador's own guidance is to pull the knob and try turning the valve stem by hand: if the stem won't move -- or the burner stays lit with the knob in OFF -- the surface burner valve is defective. The OEM valve is 00415501 (BSH/Bosch, replaces 1025809 / 415501 / 15-10-165 / AH3460983 / PS8711299; AP2832930). This is TSSA-gated gas work; we shut off the supply, replace the valve, and leak-test before re-lighting -- we never free a seized valve by force because a stem that snaps open is a live gas-leak risk.
• The cheapest "knob not working" on a Thermador is no part at all -- a cracked or worn knob collar slipping on the valve stem, so the knob spins but the flame won't change low-to-high. The surface burner knob is 00189011 (replaces 00189099 / 189099 / 1044394); some cooktop/range layouts pair a front 00189011 with a rear 00189100, and the knob bezel behind it is 00189012. We inspect the D-shaped stem and the knob's internal collar before quoting anything bigger -- a stripped knob mimics a bad valve, and swapping the $50 knob proves which it is.
• On Pro Grand and Pro Harmony cooktop-side controls, a knob that clicks but produces no spark on ANY burner points past the per-knob switch to the shared spark/ignition path -- the spark module that all the 00189008 switches feed. We confirm by turning a known-good burner: if every knob clicks-without-light, the module (BSH 00-prefix, dealer-coded by model) is the suspect, not five separate switches. If only one burner is dead, the fault stays at that knob's 00189008 switch or 00415501 valve -- we isolate single-burner vs all-burner before ordering, so a one-knob fault never gets quoted as a module.
• A Thermador burner that stays on or won't go to OFF/Simmer when the knob is turned is frequently the ExtraLow feature being misread, NOT a fault: on the star burner ExtraLow cycles the flame fully on and off by design at low settings, so a customer reports "the knob won't hold a low flame." We demonstrate ExtraLow before touching parts. Only when the burner truly won't shut off at the OFF detent do we move to the valve 00415501 or the behind-knob switch -- an honest no-charge explanation here is standard on these ranges.
• Some Thermador surface-burner knob faults are the knob/switch assembly itself rather than the gas valve -- a worn cooking-area control knob 00635400 (replaces 00619839), an element control knob 00414821 on the electric/dual-fuel surface side, or, behind the knob, a failed spark-ignition switch / potentiometer 00422748 (PS8713460) whose documented failure signs are delayed, weak, or no-response-to-knob ignition. When the knob turns freely but the burner doesn't respond, we meter the switch/potentiometer contacts on the valve shaft rather than assuming the valve.
• Note for dual-fuel Pro ranges: a knob-not-working complaint on the OVEN side is a separate fault from the surface-burner knobs -- the oven-mode selector switch 00619076 (bake/broil/convection; replaces 600602 / 610591 / 619076) controls oven function, not a cooktop burner. We scope cooktop-knob vs oven-selector at diagnosis so a surface-burner call never gets quoted an oven part, and vice versa.

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

• The recurring Thermador pattern we see across Toronto on knob-not-working calls is the behind-knob spark/ignition switch (00189008) failing after grease and boil-over moisture work down the valve shaft -- the owner reports "the knob clicks but won't light" or "one burner knob does nothing" -- and a steady share of "my low flame keeps cutting out" calls that turn out to be the ExtraLow star-burner feature working as designed, resolved on-site with no part.
• We roll to these Toronto calls with the 00189008 spark/ignition switch, the 00189011/00189100 burner knobs and the 00189012 bezel on the van; if the diagnosis is a seized or non-shutoff valve we identify 00415501 and book the BSH-channel order plus a TSSA gas leak-test, and we carry the retaining clips so a switch/knob swap is a single visit.

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