Pump runs but controller shows E05 and speed cannot be adjusted; unit may be locked at one speed or shut down.

Safety first: Disconnect power at the breaker and verify zero voltage before accessing motor wiring.

• Inspect tachometer connector: On AquaFlo variable-speed motors, locate the low-voltage harness between the control module and the motor end bell. Unplug and inspect for corrosion, bent pins, or water intrusion. Clean and reconnect firmly.
• Check harness continuity: Use a multimeter to test continuity of each tachometer wire from the control board to the motor connector. Replace the harness if any conductor is open or shorted.
• Look for physical damage: Inspect the motor end bell where the tach sensor is mounted. If cracked or water-damaged, the sensor assembly may need replacement.
• Controller reset: Perform a factory reset of the AquaFlo controller per the user manual (usually via a button sequence). Reprogram speeds and test.

If E05 persists after wiring and connector checks, the internal tach sensor or drive electronics are likely defective; replacement of the motor drive or complete motor assembly is recommended.