Washer-dryer displays E20; a general motor or drive system error on some Neff/Bosch platforms.

Safety first: Unplug the appliance. Motor and inverter circuits carry dangerous voltages.

Step-by-step checks:

• 1. Visual inspection: Remove the rear panel and inspect the motor and wiring for burn marks or loose connectors.
• 2. Test motor windings: Disconnect the motor plug and measure resistance between the windings (for brushless motors). All phases should be similar. A short to earth or a large imbalance indicates a faulty motor.
• 3. Check hall sensor (if fitted): Inspect the hall sensor connector on the motor. Replace the sensor or motor if damaged.
• 4. Inverter module: The inverter is often integrated into the main control. If the motor tests good but E20 persists, the inverter/control board likely needs replacement.

When to call a technician: Motor and inverter diagnosis is advanced; professional service is strongly recommended.