Display shows HTR or HEAT FAIL, water does not reach set temperature.

Safety: Turn off power and verify with a non-contact voltage tester before touching heater wiring.

• Inspect heater connections: In the equipment bay, locate the heater terminals on the control pack. Check for loose, burnt, or corroded connections and tighten as needed.
• Check for error codes: Note any accompanying sensor or flow codes that may be preventing the heater from energizing.
• Measure heater resistance: With power OFF and wires removed from the heater terminals, use a multimeter to measure resistance across the heater element. An open circuit (infinite resistance) indicates a failed element.
• Verify power to heater: With a qualified person and proper safety, measure voltage at the heater terminals when the spa is calling for heat. No voltage suggests a control board or relay issue.

Heater and high-voltage diagnostics should generally be performed by a licensed spa technician. Replace the heater assembly or control pack as indicated by test results.