Bosch Washer F42 Error Code — What It Means
The F42 error code on Bosch washers indicates a motor-related fault, typically a problem in the motor or tachometer feedback circuit. The control board has detected an abnormal motor condition and halted the cycle to protect the system. This code is grouped with F43 and F44 in Bosch fault references, all of which point to motor issues rather than drain, door, or heater problems. The washer may fail to start, stop mid-cycle, or refuse to spin when F42 is active.
Common Causes
- Worn or failed carbon brushes The motor brushes have worn down, lost spring pressure, or are sticking, preventing proper motor operation and feedback.
- Loose or damaged motor connector The motor wiring connector block is corroded, loose, heat-damaged, or has broken terminals that interrupt the signal.
- Faulty tachometer feedback circuit The tacho sensor or its wiring is defective, sending incorrect speed feedback to the control board.
- Defective motor winding or assembly The drive motor itself has failed due to shorted or open windings, bearing seizure, or internal damage.
- Damaged motor harness wiring The wire harness between the control and motor has rubbed through, developed an open circuit, or has corrosion at the terminals.
Step-by-Step Fix
- Unplug the washer and pull it away from the wall to access the rear panel or bottom access area, depending on your Bosch model.
- Locate the drive motor (typically at the bottom rear) and inspect the connector block where the harness plugs into the motor for heat damage, corrosion, or loose pins.
- Check the motor wiring harness from the control board to the motor for any visible damage, pinched or rubbed-through insulation, or loose connections.
- Remove the motor brushes by unclipping or unscrewing the brush caps on each side of the motor, then pull out the brushes and inspect for wear (less than about 1/2 inch remaining), uneven wear, or sticking in the holders.
- Inspect the tachometer connections on the motor (if your motor has a separate tacho wire or sensor) for loose or corroded terminals, and verify continuity in the tacho wiring if you have a multimeter.
- Replace worn brushes or the motor as needed: if brushes are good and wiring checks pass, the motor winding or internal feedback device is likely faulty and the motor should be replaced.
- Clear the fault code after repair by turning the dial to off, rotating it to the 6 o’clock position, holding the spin button while turning to 7 o’clock for about five seconds, then returning to off and powering on to test a cycle.
Parts Often Needed
| Part | Notes |
|---|---|
| Motor carbon brush set (Bosch washer) | Amazon | Match the brush part number to your motor model, often sold in pairs with springs and holders. |
| Bosch washer drive motor assembly | Amazon | Required if brushes and wiring are good but the motor winding or tachometer is defective, verify E-Nr model compatibility. |
| Motor wiring harness (Bosch washer) | Amazon | If the connector or harness itself is heat-damaged or has broken terminals, replace the entire harness segment. |
When to Call a Pro
Call a professional if you are not comfortable working with electrical connections, disassembling the washer cabinet, or handling the motor removal and installation. If you have replaced the brushes and checked all wiring but the F42 fault persists, a technician with a multimeter and Bosch service documentation can test motor windings, tacho feedback voltage, and control board outputs to isolate the fault. A pro can also verify the exact diagnostic procedure for your specific E-Nr model number, since Bosch platforms vary in motor type and feedback circuit design.