How to Fix / Troubleshooting

Safety first: Turn off power before accessing heater wiring.

Check mode and setpoint: Ensure the spa is in Standard mode and the set temperature is higher than the current water temperature.
Listen for relay click: When heating should start, listen near the control pack for a relay click. No click may indicate a control issue.
Test heater (advanced): With power off and heater wires disconnected, measure resistance across the heater terminals. An open reading indicates a failed heater element that must be replaced.
Inspect wiring: Confirm heater wires are tight and not burned at the terminals.
Replace faulty part: Replace the heater assembly if open. If heater is good but never receives power, the control board/relay is likely defective.

Spa powers on but will not heat; temperature remains below setpoint with no error code.

Possible Causes