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Error code reference

Bosch Range Error Code ER25

Electric cooktop MTwisT control false connection mains fault.

Bosch codesBosch range codes

Electric cooktop MTwisT control false connection mains fault.

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What ER25 means on a Bosch range

The ER25 error code on a Bosch range indicates a false connection mains fault within the Electric cooktop MTwisT control system. The MTwisT system is Bosch's induction or electric cooktop control interface, and this fault specifically points to an issue with how the cooktop control module is receiving or interpreting the incoming mains power supply. A "false connection" fault means the control electronics have detected an anomaly in the way line voltage is being delivered or sensed, which could involve incorrect phase wiring, missing neutral connections, or improper voltage levels reaching the control board.

The mains fault classification means the problem originates at the point where household electrical supply interfaces with the appliance's cooktop control circuitry. This could stem from a wiring error at the terminal block, a loose or corroded connection in the supply leads, or a fault within the MTwisT control module itself that is misreading the incoming supply. In some cases, the issue can also arise from an upstream electrical problem such as a tripped breaker, an under-voltage condition at the outlet or hardwire connection, or an incorrectly configured supply voltage for the appliance model.

Because this fault is rooted in the mains electrical supply to the cooktop control, diagnosis should begin at the terminal block and supply wiring before condemning the control board. Inspecting for loose conductors, verifying correct wire placement according to the terminal labeling, and confirming proper supply voltage with a multimeter are critical first steps. If wiring is confirmed correct and supply voltage is within spec, the MTwisT control module itself may require replacement.

Source: manufacturer service documentation.

Common causes of ER25

  1. 01

    Loose or incorrect terminal block wiring

    Wiring / connection

    A wire that is not fully seated, incorrectly positioned, or has backed out of the terminal block can cause the MTwisT control to detect a false mains connection. Visually inspect the terminal block for any loose, burnt, or misplaced conductors.

  2. 02

    Missing or faulty neutral connection

    Wiring / connection

    An open or high-resistance neutral conductor in the supply wiring can cause the cooktop control to misread the mains configuration. Check the neutral terminal for continuity and secure connection.

  3. 03

    Incorrect supply voltage

    Wiring / connection

    If the incoming supply voltage is outside the acceptable range for the appliance, the MTwisT control may flag a mains fault. Use a multimeter to verify that the supply voltage at the terminal block matches the range's rated voltage requirements.

  4. 04

    Corroded or burnt terminal connections

    Part replacement

    Corrosion or heat damage at the supply terminals can introduce resistance that distorts the voltage signal seen by the control module. Inspect all terminal connections for discoloration, pitting, or carbon deposits.

  5. 05

    Faulty MTwisT control module

    Part replacement

    If all wiring and supply voltage checks pass, the MTwisT control board itself may have an internal fault causing it to misinterpret the mains input. Replacement of the control module would be required.

See the test procedure for each cause

Frequently asked questions about ER25

What does ER25 mean on a Bosch range?
ER25 on a Bosch range indicates a false connection mains fault in the electric cooktop MTwisT control system. It means the cooktop control electronics have detected an anomaly in how the incoming mains power supply is being delivered or read. This is typically related to wiring at the terminal block or an issue with the supply voltage reaching the control module.
Can I fix the ER25 error on my Bosch range myself?
Basic checks such as verifying the circuit breaker and inspecting for obviously loose wires at the terminal block can be done by a knowledgeable DIYer, but working inside a range near mains wiring carries serious electrical shock risk. Because this fault directly involves the high-voltage supply connections, most homeowners should have a qualified appliance technician perform the diagnosis and repair. Do not use the cooktop while this fault is active.
Is the ER25 error on a Bosch range a safety concern?
Yes, this error should be treated as a safety concern because it indicates a problem with the mains electrical supply to the cooktop control. A false connection or wiring fault in the mains supply can pose a risk of electrical damage to the appliance or, in severe cases, a shock or fire hazard. Avoid using the cooktop until the fault has been diagnosed and resolved by a qualified technician.
Will resetting the Bosch range clear the ER25 error code?
Resetting the range by cycling the circuit breaker may temporarily clear the display, but the ER25 error will return if the underlying mains wiring or connection fault has not been corrected. A reset does not fix a loose terminal, incorrect wiring, or a faulty control module. The root cause must be identified and repaired for the fault to be permanently resolved.
How much does it cost to repair the ER25 error on a Bosch range?
Repair costs vary depending on the root cause. If the issue is simply a loose or incorrectly seated wire at the terminal block, the labor cost for a service call is typically the primary expense, often ranging from $75 to $200 depending on your location. If the MTwisT control module requires replacement, parts and labor combined can range from $200 to $500 or more, depending on the specific model and part availability.

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