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Error code reference

Bosch Range Error Code ER24

Electric cooktop MTwisT control wrong number of relays.

Bosch codesBosch range codes

Electric cooktop MTwisT control wrong number of relays.

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What ER24 means on a Bosch range

ER24 on a Bosch range with an Electric cooktop MTwisT control system indicates that the control module has detected an incorrect number of relays in the cooktop relay circuit. The MTwisT system is Bosch's induction or electric cooktop control architecture that manages power delivery to individual cooking zones through a relay bank. When the control board performs its internal self-check, it counts the active relay signals and compares that number against the expected configuration programmed into the module. If the count does not match, ER24 is triggered and cooktop operation is typically disabled as a safety measure.

The most common hardware causes include a failed relay on the power control board, a wiring fault between the relay board and the main control module, or a complete failure of the relay board assembly itself. Relays can fail in an open or shorted state, either of which changes the relay count the control module reads during its diagnostic cycle. Connector corrosion or a loose harness connection can also cause intermittent relay signal drops that produce this error.

Because this fault involves the cooktop's power switching components, it is not a condition that can be resolved through a simple reset alone. A technician will need to inspect the relay board, verify the wiring harness integrity, and potentially replace the defective relay assembly or main control board. Given the high-voltage nature of the relay circuit in an electric range, this repair should be approached with appropriate safety precautions including disconnecting power before any component inspection.

Source: manufacturer service documentation.

Common causes of ER24

  1. 01

    Failed relay on the power control board

    Part replacement

    One or more relays on the cooktop relay board may have failed in an open or shorted state, causing the control module to count an incorrect number of active relays during its self-check. A technician can inspect the relay board for signs of burning, pitting, or failed relay contacts.

  2. 02

    Faulty relay board assembly

    Part replacement

    The entire relay board may have failed, making it unable to properly report its relay configuration to the main control module. This is more likely if multiple relays or board components show damage.

  3. 03

    Loose or damaged wiring harness connection

    Wiring / connection

    A disconnected, corroded, or damaged connector between the relay board and the control module can interrupt relay signal communication, causing an incorrect relay count. Inspecting all harness connectors in the cooktop control circuit for security and corrosion is an important early diagnostic step.

  4. 04

    Faulty main control module

    Part replacement

    If the main control board's relay-counting circuit is defective, it may misread a correctly functioning relay bank and falsely trigger ER24. This is typically diagnosed after the relay board and wiring have been confirmed to be in good condition.

  5. 05

    Wiring short or open circuit in the relay signal circuit

    Wiring / connection

    A chafed, pinched, or broken wire in the signal circuit between the control module and the relay board can produce an intermittent or permanent incorrect relay count. Inspection of the wiring harness for physical damage along its routing path can help identify this cause.

See the test procedure for each cause

Frequently asked questions about ER24

What does ER24 mean on a Bosch range?
ER24 indicates that the MTwisT cooktop control system has detected an incorrect number of relays in the cooktop's power switching circuit. The control module performs a self-check and counts active relay signals, and ER24 appears when that count does not match the expected value. The cooktop is typically disabled when this fault is active to prevent unsafe operation. A relay board failure, wiring fault, or control module issue is usually responsible.
Can I fix ER24 on my Bosch range myself?
Some basic checks, such as inspecting visible wiring harness connectors for looseness or corrosion, can be performed by a knowledgeable DIYer after the appliance is completely unplugged from power. However, diagnosing and replacing a faulty relay board or control module requires working inside a high-voltage appliance, which carries serious safety risks. For most homeowners, this repair is best left to a qualified appliance technician.
Is it safe to use my Bosch range while ER24 is displayed?
You should not attempt to use the electric cooktop while ER24 is active. The control system disables the cooktop specifically because the relay configuration cannot be confirmed as correct, and operating the cooktop in this state could pose a risk. The oven section of the range may still function depending on the model, but the cooktop should remain off until the fault is properly diagnosed and repaired.
Will resetting my Bosch range clear the ER24 error code?
A power reset, such as unplugging the range or cycling the circuit breaker for a few minutes, may temporarily clear the error if the fault was caused by a transient signal issue. However, if there is an underlying hardware problem such as a failed relay or damaged wiring, the ER24 code will return once the control module runs its self-check again. A reset alone is not a fix for this fault.
How much does it cost to repair a Bosch range showing ER24?
Repair costs for ER24 depend on which component is at fault. A wiring harness repair is generally the least expensive option, while replacing a relay board or main control module carries higher parts and labor costs. In total, you can typically expect to spend somewhere in the range of $150 to $500 or more depending on the specific parts needed, labor rates in your area, and whether the range is still under warranty.

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