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Error code reference

Bosch Cooktop Error Code ER 35

Selection of keys error detected by the mTwist control system.

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Selection of keys error detected by the mTwist control system.

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What ER 35 means on a Bosch cooktop

ER 35 on a Bosch cooktop indicates that the mTwist control system has detected a key selection error. The mTwist system is Bosch's touch and rotary control interface, which interprets user input from the control panel to regulate burner zones, power levels, and other cooktop functions. When the system detects an invalid, conflicting, or unresolvable key input state, it triggers this error to prevent unintended operation.

The fault typically points to a problem within the control panel assembly itself. This can involve stuck or continuously activated touch keys, a damaged capacitive sensing layer beneath the glass surface, or a failure in the control board that processes input signals from the panel. Liquid intrusion from spills is a common contributing factor, as moisture can create phantom key presses or short circuits across the touch sensor contacts, confusing the mTwist controller into registering an impossible combination of simultaneous inputs.

Because the mTwist control system relies on precise signal differentiation between individual keys, even partial damage to the sensing circuitry or the ribbon cable connecting the panel to the main control board can produce this error. In some cases the error may appear intermittently if the underlying cause is moisture-related or a loose connection, while persistent display of ER 35 at startup typically points to a hardware failure requiring component replacement.

Source: manufacturer service documentation.

Common causes of ER 35

  1. 01

    Liquid or moisture intrusion on the control panel

    Wiring / connection

    Spills or cleaning liquid seeping beneath the glass surface can create false or simultaneous key signals that the mTwist system cannot resolve. Inspect the panel surface for moisture and allow it to dry completely before retesting.

  2. 02

    Stuck or continuously activated control key

    Wiring / connection

    A physically stuck touch key or a deformed area of the control glass can register as a constant keypress, triggering the selection error. Inspect all key zones for visible damage, debris, or abnormal pressure points.

  3. 03

    Faulty control panel or touch sensor assembly

    Part replacement

    Damage to the capacitive sensing layer or internal circuitry of the control panel can produce invalid key states that trigger ER 35. If the error persists after ruling out moisture and physical obstruction, the panel assembly likely needs replacement.

  4. 04

    Damaged or loose ribbon cable between panel and control board

    Wiring / connection

    The ribbon cable connecting the control panel to the main control board can develop intermittent faults due to heat exposure, improper seating, or physical damage. A poor connection can cause erratic key signal transmission that the mTwist system interprets as a selection error.

  5. 05

    Failed main control board

    Part replacement

    If the control board's input processing circuitry fails, it may misread or fail to differentiate key signals even when the panel itself is intact. This is less common but should be considered when the panel and ribbon cable check out as functional.

See the test procedure for each cause

Frequently asked questions about ER 35

What does ER 35 mean on a Bosch cooktop?
ER 35 means the mTwist control system has detected a key selection error on the cooktop's control panel. The system identified an invalid or unresolvable input state from one or more keys. This causes the cooktop to disable itself to prevent unintended burner operation. The fault can originate from moisture, a stuck key, a damaged control panel, or a control board issue.
Can I fix ER 35 on my Bosch cooktop myself?
Some causes of ER 35 are user-serviceable. Start by powering down the cooktop at the circuit breaker for several minutes, then inspect the control panel for moisture or debris before restoring power. If the error was triggered by a spill, thoroughly drying the panel surface may resolve it. If the error returns consistently, internal component replacement by a qualified technician is likely required.
Will resetting the cooktop clear the ER 35 error?
A power reset by turning off the circuit breaker for at least 5 minutes may clear ER 35 if the cause was a temporary condition such as a moisture-related false keypress. However, if an underlying hardware fault exists, such as a damaged control panel or failed board, the error will return after reset. A reset is a useful first diagnostic step but is not a repair.
Is it safe to use my Bosch cooktop when ER 35 is displayed?
You should not attempt to operate the cooktop while ER 35 is active. The error indicates the control system cannot reliably interpret user input, which means burner zones may not respond predictably. The cooktop disables itself as a safety measure, and bypassing or ignoring this condition is not recommended.
How much does it cost to repair a Bosch cooktop showing ER 35?
Repair costs depend on the root cause. If only cleaning or a reset is needed, there may be no parts cost beyond a service call fee, which typically ranges from $75 to $150. Replacing a control panel assembly or main control board can bring total repair costs into the range of $200 to $500 or more, depending on the specific model and local labor rates.

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