Pump will not start, digital controller displays E01 immediately when START is pressed.

Safety first: Isolate power at the pool plant room isolator and verify with a tester before touching the pump or wiring.

Step-by-step checks:

• Check for mechanical seizure: Remove the pump lid on the Certikin pump, take out the strainer basket and check for debris. Try to rotate the impeller shaft by hand (from the back of the motor or via the fan). If it is stiff or seized, the wet end or bearings may be jammed.
• Inspect for blockages: Check the pump strainer basket, suction line, and non-return valve for stones, leaves, or plastic that could lock the impeller.
• Verify supply voltage: Using a multimeter, confirm that the controller is receiving the correct voltage (e.g. 230 V single phase for Certikin Aquaspeed / Swimflo models). Undervoltage or overvoltage can trigger E01.
• Check motor windings: With power isolated and motor disconnected, measure resistance between motor terminals and to earth. Very low resistance or continuity to earth indicates a shorted winding.
• Reset overload: Some Certikin motors have a manual reset thermal overload on the motor body. Press the reset button if present and retry.

If E01 persists after clearing blockages and confirming correct voltage, the motor may be damaged and should be tested or replaced by a qualified pool technician or electrician.