Display or indicator light for 'descale' remains on even after descaling.

Safety first: Unplug before opening the housing.

• Follow reset steps: Consult the Tristar manual for the exact button sequence to reset the descale light. Often this involves holding a specific button for several seconds after a descale cycle.
• Run another rinse cycle: Sometimes the control requires a certain volume of water to clear the indicator. Run 1–2 full tanks of clean water through the machine.
• Check flow meter (advanced): Ensure the flow meter is functioning and its connector is secure. If it does not send pulses, the control will not register the descale as complete.

Note: If the light remains on but the machine works normally, it may be a minor firmware issue; you can continue using the unit but monitor for real scale buildup.