Display shows OHS or OH2 and spa shuts down; often triggered by high-limit sensor rather than main temperature sensor.

Safety: Turn off power and allow the spa to cool completely. Do not reset repeatedly without finding the cause.

• Check for flow restriction: Clean or remove the filter and verify strong flow from jets and circulation return.
• Inspect high-limit sensor: Locate the high-limit sensor on the heater tube (often a separate sensor or manual reset). Ensure it is firmly attached and not corroded.
• Reset (if manual type): Some Jacuzzi heaters have a small red reset button on the high-limit. Once cooled, press gently until it clicks. If it trips again, stop using the spa.
• Look for dry-fire signs: Check the heater tube for discoloration or burnt smell, which can indicate the heater ran without water.

Repeated OHS trips indicate a serious issue such as a failing heater relay or circulation problem. Have a qualified technician test the heater circuit and replace the high-limit sensor or control board as needed.