Bosch Cooktop Won't Start

Most Likely Cause#

About 40% of Bosch cooktops that will not start are not broken at all — they are locked out, unpowered, or waiting on the right pan. Before any repair, clear the control lock, confirm the circuit, check for induction-compatible cookware, and verify the gas supply. Beyond those, the leading real fault on gas models is a failed spark igniter module at about 30%, and on induction models a failed control board at about 25% or a pan-detection fault at about 20%. A tripped thermal cutout and a gas valve solenoid round out the list.

Quick Checks First (about 40% of Calls)#

• Control lock: hold the lock or key icon for about three seconds to toggle it off; a lit lock icon means it is active.
• Power: check the breaker. Induction and electric Bosch cooktops need a dedicated 240V/40A circuit; gas ignition runs on a 120V/15A circuit, and a tripped kitchen GFCI can kill the sparker even while gas still flows.
• Induction cookware: a zone will not activate without ferromagnetic cookware — if a magnet does not stick to the pan base, it will not work on induction.
• Gas supply: confirm the shutoff valve behind the cooktop is parallel to the pipe (open), not perpendicular.

Symptom-to-Cause Table#

The Causes in Detail#

On gas models a central spark module fires every igniter at once, so no clicking anywhere points at the module or its power, while clicking at only one burner is a cracked igniter or a loose wire. On the FlameSelect models (NGM8056UC and NGM8656UC) a safety interlock shuts gas if the flame sensor never confirms ignition — clean a carbon-fouled sensor tip before condemning parts. Induction control boards fail from power surges, showing a dead or erratic display and often codes E0 or E6, and a pan-detection coil that opens leaves one zone unable to see cookware that works elsewhere. A blown thermal cutout disables the cooktop until it cools, frequently alongside a failed cooling fan (E3 or E5). And a gas valve solenoid that no longer holds open is a gas-line repair for a licensed fitter.

How to Narrow It Down#

1. Run the quick checks first — lock, breaker, cookware, gas valve — since they explain roughly 40% of calls.
2. On induction, test with a cast-iron pan; if one zone works and another does not, the fault is zone-specific.
3. On gas, listen: no click means power or the spark module, click with no gas means the solenoid or supply, and click with gas but no light means the igniter gap or position.
4. Read any error code — E0, E3, E5, E6, and E9 each point at a specific subsystem.
5. To open the electronics, remove the cooktop (Torx T20) and inspect the board for a bulged capacitor or a burnt trace.

Repair or Replace?#

Control-lock and power issues cost nothing, and an igniter, spark module, or cooling fan is a bounded part on an otherwise sound cooktop — so most will-not-start faults are worth fixing. An induction control board or coil assembly is the priciest case and still usually beats replacing a premium cooktop, and a gas solenoid is a safety repair for a pro. EasyBear can run the checks, read the codes, and bring the right Bosch part — book now.

Prevent It Coming Back#

• Learn the control-lock gesture so an accidental lock does not read as a failure.
• Put the cooktop on its own correctly rated circuit and add surge protection for the induction board.
• Keep flame-sensor tips and burner ports clean on gas models.
• Use induction-compatible cookware and keep the cooling-fan intake clear on induction units.