Vacuum shows E9 or a fan icon with an exclamation mark; motor makes a rough noise and suction is unstable.

Safety first: Remove the battery and wait for all moving parts to stop. Opening the motor housing exposes high‑speed components; only proceed if you are confident and the unit is out of warranty.

• Step 1 – Basic checks: Ensure filters are clean and airflow is not restricted, as severe load changes can trigger speed errors.
• Step 2 – Listen for mechanical noise: With the vacuum briefly powered (battery installed), listen for grinding or whistling from the motor. Immediately switch off if the noise is severe.
• Step 3 – Inspect internal wiring (advanced): Open the main body housing and locate the motor assembly and its connector to the control PCB. Check for loose plugs, broken wires, or signs of overheating. Reseat connectors.
• Step 4 – Replace motor assembly: If the motor bearings are noisy or the tachometer sensor (often integrated into the motor) is faulty, replace the complete motor assembly with the correct Princess motor module.
• Step 5 – Replace control PCB if needed: If a new motor does not resolve E9, the motor driver circuit on the control PCB is likely defective and should be replaced by a technician.