Bosch Stove Repair in Toronto — Surface element stuck on high

• On a Bosch radiant glass-top range (HEI-prefix 800-series, e.g. HEI8054U / HEIP054U) a zone that heats full-blast no matter where the knob sits is almost always a welded surface-element control switch (infinite switch / energy regulator), not the element. That switch sets power by rapidly cycling the element on and off at a variable duty; when its contacts fuse closed in the full-on position it feeds continuous line voltage and the zone runs at maximum. The genuine parts are the Bosch 00422133 energy regulator / infinite switch (PartSelect PS8713176 / AP3723298, which supersedes / cross-references 1050277 / 422133 / AH3462872 / EA3462872 / PS3462872) and the companion 00632570 surface-element control switch (OEM fitment confirmed for HEI8054U and HEIP054U builds). We isolate power and meter the switch contacts through their cycle before condemning it -- a stuck-on zone with the knob at OFF is its signature, and the switch is a fraction of a board's cost.
• A zone that keeps glowing after the knob is turned fully OFF -- where only killing the breaker stops it -- points past the infinite switch to a stuck-closed relay or triac on the surface-element control board. RepairClinic documents this as the canonical 'surface element won't turn off' cause: a board relay shorts closed and sends continuous voltage to the heating circuit regardless of the user setting. On Bosch radiant builds this is the model-coded BSH surface-element / relay board, the most expensive part in this chain. We confirm it the right way: only after the infinite switch (00422133 / 00632570) for that zone meters good do we condemn the board, because a welded switch and a stuck relay read the same to the cook but cost very different to fix.
• When the complaint is an induction zone (HII-prefix slide-in range or NIT-prefix cooktop such as NIT3065UC / NIT5065UC / NIT8065UC) that surges to full power or won't respond to the touch slider, the fault sits in the induction power board, not a mechanical switch -- there is no infinite switch on induction. These cooktops run two power boards: the primary power board 00745798 (master power) and the secondary power control board 00748595 (which regulates the power delivered to the coils). A failed IGBT / power stage on that board can lock a zone's output high. Because one board drives a pair of zones, we isolate which zones misbehave and meter the board's supply and connectors before ordering -- these are ~$400-$600 boards, so accurate diagnosis keeps the quote off a full-cooktop replacement.
• Before any induction board is condemned for a 'stuck on / runaway' complaint we clear the cheap causes Bosch publishes first. A flashing lowercase 'e' on the panel means the control glass is wet or something is resting on it -- the touch logic misreads and the zone can latch or refuse a level change; we dry the panel and clear the surface. E011 is a control-panel / touch-key fault (a stuck or continuously-pressed key, often a wet panel) -- we wipe the panel dry, then kill the breaker for ~5 minutes and restore power. E005 is a different animal: a communication fault between the user-interface / touch module and the main control board (a contact issue at the X12 connector or the ribbon cable), and Bosch's documented first step is the same ~5-minute breaker reset, which clears the transient ones. A flashing 'e' or E011 that clears on a wipe-and-reset, or an E005 that clears on the breaker cycle, is a no-part repair, and skipping that step is how a good 00745798 / 00748595 board gets needlessly quoted.
• A radiant zone stuck on can occasionally be the element itself shorting internally rather than its control: the Bosch dual 5"/8" radiant element 00499757 (or the companion radiant element 00499573, shared across Bosch/Thermador/Gaggenau glass-tops) can fail with a turn-to-turn or turn-to-chassis short that keeps the coil energized hotter than commanded. This is the less common runaway path -- the infinite switch and relay board are the usual culprits -- so we meter the element cold for an abnormal low resistance / continuity to its sheath before replacing it, and confirm the model and wattage by tag since these elements are shared across BSH platforms.
• An intermittent 'one zone sometimes ramps to full and won't come down' on a radiant range, where the switch and board both test good cold, is frequently a heat-degraded or arcing terminal at the infinite-switch tab or the element receptacle: heat-cycling oxidizes a marginal crimp until the contact intermittently bridges or hangs, so the duty signal sticks under load. We inspect and re-terminate the receptacle and the switch tabs (00422133 / 00632570) rather than throwing a board at a connection fault -- this is the runaway that disappears on the bench and gets misdiagnosed as a recurring bad board.
• Naming the platform from the model tag is the first move on every 'stuck on high' Bosch, because the fix is completely different across the three 800-series worlds: a radiant glass-top (HEI/HES-prefix) is an infinite-switch or relay-board fault on real BSH parts (00422133 / 00632570 / model-coded board); an induction (HII/NIT-prefix) is a power-board fault (00745798 / 00748595) with no mechanical switch to blame; and a knob that physically won't return from HIGH on the range body is mechanical, not electrical. We decode the model before ordering so we don't fit a radiant infinite switch to an induction deck that has none.

Bosch surface element stuck on high in Toronto — the local specifics

• The recurring Toronto pattern on Bosch 'element-stuck-on-high' is that it sorts cleanly by platform once we read the model tag, and the cheap fix wins more often than the customer expects. On the radiant 800-series (HEI/HES) the stuck-on-max zone is almost always a welded infinite switch (00422133 / 00632570) or, when it stays hot with the knob at OFF, a stuck-closed relay on the surface-element board -- and we meter the switch before ever quoting the board. On induction (NIT/HII) the same complaint is a power-board (00745798 / 00748595) fault or a wet-panel flashing 'e' / E011, or an E005 user-interface-to-control-board communication fault, that clears on a dry-and-reset, so we run Bosch's documented breaker reset and panel wipe before condemning any electronics. Stated qualitatively, not as a job count.
• We carry the two common Bosch radiant infinite switches -- 00422133 (PS8713176) and 00632570 -- plus a surface-element receptacle/terminal repair kit and a meter to these calls, so a confirmed welded-switch or burnt-terminal runaway is fixed on the first visit. For induction stuck-on/runaway zones we bring the meter and Bosch's reset procedure first; the 00745798 / 00748595 power boards are model/serial-ordered after we confirm which zone pair and which board, rather than carried speculatively.

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 surface element stuck on high guide.