Display shows PSE or PUMP SENSOR ERROR; solar pump does not start or shuts down immediately.

Safety: Turn off power at the breaker before opening the Fafco controller or touching pump wiring.

• Inspect pump wiring: Remove the controller cover and verify that the solar pump hot, neutral, and ground wires are firmly secured at the relay or terminal block. Tighten any loose connections.
• Check pump amperage: With a clamp meter and power restored, run the solar pump manually (if possible) and measure current draw. Compare to the pump nameplate and controller specifications. Excessive current can trigger PSE.
• Look for shorts: Inspect the pump cable from controller to pump for cuts, crushed sections, or water intrusion at junction boxes. Repair or replace damaged cable.
• Controller current sensor: If wiring and pump are normal, the internal current-sensing circuit on the Fafco board may be faulty. Visual inspection may show burnt components near the pump relay.
• Test with known-good pump: If available, temporarily connect a small test pump to the controller output to see if PSE persists. If it does, the controller board likely needs replacement.