Unit displays E12 and shuts off shortly after start; fan noise may be abnormal.

Safety first: Disconnect power and wait for all moving parts to stop before opening the motor housing.

• Access the motor assembly: Remove the rear or bottom cover to expose the suction motor and its attached tachometer sensor (often a small PCB or Hall sensor).
• Inspect tach components: Check that the magnet or encoder ring on the motor shaft is intact and not loose. Ensure the sensor is positioned correctly and not contaminated with dust.
• Check wiring: Verify that the tach sensor wires are firmly connected to both the sensor and the main PCB, with no breaks or chafing.
• Test sensor output: If equipped and you have the tools, spin the motor by hand and measure for pulsed voltage from the sensor. No pulses indicate a failed sensor.
• Replace faulty parts: Replace the tach sensor module or entire motor assembly if the sensor is integrated. If the sensor tests good, suspect the motor control circuitry on the main PCB.