H2
MSPA
Critical Overheat Lockout
MSPA spa shows H2 and heating is disabled; water may be very hot.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Heater stuck on due to relay failure, Flow completely blocked through heater, High-limit sensor failed low, User set temperature too high in hot climate
How to Fix / Troubleshooting
Safety first: Do not enter the spa if water exceeds 40°C. Unplug immediately.
- Allow cooling: Leave the cover open and allow the water to cool naturally to below 35°C before further work.
- Check filter and flow: Clean or replace the MSPA filter cartridge and ensure strong flow from the outlet. Remove any obstructions.
- Test heater control: After cooling, reconnect power and set a low temperature (e.g., 30°C). If the heater energizes and continues heating past the set point, the heater relay on the PCB is likely stuck and the PCB must be replaced.
- Replace high-limit sensor: If H2 appears even with cool water and the heater is off, the high‑limit sensor may be reading incorrectly and should be replaced.
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Repair Difficulty
Hard
4/5
Required Part
MSPA High-Limit Temperature Sensor
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