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Error code reference

Miele Washer Error Code F4058

Tachogenerator signal too small.

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Tachogenerator signal too small.

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  • Step-by-step tests with expected resistance, voltage, and continuity values
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  • Verified part numbers when replacement is required
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What F4058 means on a Miele washer

Error code F4058 on a Miele washer indicates that the tachogenerator signal is too small, meaning the motor control system is receiving a feedback signal from the tachogenerator that falls below the expected threshold. The tachogenerator, also called a tacho, is a small sensor device attached to or integrated with the drive motor that generates an electrical signal proportional to motor rotation speed. The machine's control board continuously monitors this signal to regulate spin speeds, detect motor stalls, and ensure proper drum operation throughout each wash cycle.

When the tachogenerator output is weaker than expected, the control board cannot accurately determine motor speed. This can occur due to a failing tachogenerator coil with degraded output, poor or corroded electrical connections between the tacho and the control board, or physical damage to the tacho sensor itself. A worn motor with reduced rotational efficiency may also produce a diminished tacho signal because the motor is not spinning as freely or consistently as required.

Because the signal is described as too small rather than absent entirely, the motor is likely still functioning to some degree, but the feedback voltage or pulse amplitude is insufficient for reliable speed control. Technicians should inspect the wiring harness and connectors between the motor and control board for corrosion, fretting, or loose terminals before condemning the tachogenerator or motor. If wiring checks out, resistance and output testing of the tachogenerator winding is the next logical step.

Source: manufacturer service documentation.

Common causes of F4058

  1. 01

    Faulty or degraded tachogenerator

    Part replacement

    The tachogenerator coil can weaken over time, producing a signal that is below the minimum threshold required by the control board. Testing the tacho winding for correct resistance and output voltage will confirm this.

  2. 02

    Loose or corroded wiring connections

    Wiring / connection

    Poor contact at the connector between the tachogenerator and the control board can reduce the signal level significantly. Inspect all terminals and connectors along the motor harness for corrosion, fretting, or backing-out pins.

  3. 03

    Damaged motor wiring harness

    Part replacement

    Chafed, pinched, or broken wires in the harness running from the motor to the control board can cause signal loss. A visual inspection of the full harness routing and a continuity check of each conductor will identify breaks.

  4. 04

    Worn or failing drive motor

    Part replacement

    A motor with worn bearings or brush wear may not spin at consistent speed, resulting in an inconsistent or low-amplitude tachogenerator output. Unusual motor noise or heat during operation can point to this cause.

  5. 05

    Control board fault

    Part replacement

    If the tachogenerator, wiring, and motor all test within specification, the control board's input circuit for the tacho signal may have failed and is misreading the signal level. This is the least common cause and should be diagnosed only after ruling out all other possibilities.

See the test procedure for each cause

Frequently asked questions about F4058

What does F4058 mean on a Miele washer?
F4058 means the tachogenerator signal received by the control board is too small. The tachogenerator is a sensor on the drive motor that reports how fast the motor is spinning. When its output falls below the acceptable threshold, the machine cannot regulate the drum speed and will fault out. The cause is typically a failing tachogenerator, a connection problem in the motor wiring, or a worn motor.
Can I fix F4058 on my Miele washer myself?
Some DIY-level repair is possible, particularly checking and cleaning wiring connections along the motor harness. However, testing the tachogenerator output and replacing motor components requires basic electrical knowledge and a multimeter at minimum. If you are not comfortable working around appliance wiring, a qualified technician is recommended for this repair.
Is it safe to keep using my Miele washer when F4058 is displayed?
It is not advisable to continue running the washer with this error active. Because the machine cannot accurately monitor motor speed, it may run the motor under unsafe conditions or fail unpredictably mid-cycle. Stopping use until the fault is diagnosed helps prevent potential damage to the motor or control board.
Will resetting my Miele washer clear the F4058 error?
A reset may temporarily clear the code and allow a cycle to start, but F4058 will return if the underlying hardware fault is not corrected. If the tachogenerator signal remains too small, the machine will detect the condition again and stop. A reset is only useful as a quick test to confirm the fault is active and repeatable.
How much does it cost to repair a Miele washer with error F4058?
Repair costs vary depending on the root cause. If only wiring cleaning or connector repair is needed, costs can be minimal. Replacing a tachogenerator or motor typically ranges from a few hundred dollars into the higher hundreds when including parts and labor. A control board replacement would represent the higher end of that range.

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