E05
Lay-Z-Spa Temperature Sensor Discrepancy / Dual Sensor Mismatch

Lay-Z-Spa shows E05 and will not heat; filter may still operate.

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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

Disagreement between inlet and outlet temperature sensors, One of the dual NTC sensors failed or drifted, Loose sensor connector on control PCB, Control board calibration fault

How to Fix / Troubleshooting

Safety first: Turn off and unplug the spa before inspecting the pump/heater unit.

  • 1. Power cycle: Unplug the spa for 10 minutes, then reconnect and reset the RCD. Sometimes transient sensor errors clear after a full reset.
  • 2. Check actual water temperature: Use a separate thermometer to compare with the displayed temperature. If the reading jumps or is unstable, a sensor is likely failing.
  • 3. Inspect for external damage: Look for crushed, cut, or chewed sensor cables entering the pump housing. Rodent damage or pinched cables can cause intermittent readings.
  • 4. Descale sensor area: If accessible, gently descale the sensor pockets in the water path using a mild descaler and soft brush, then flush thoroughly.
  • If E05 persists: One of the temperature sensors or the control PCB is faulty. These components are integrated into the pump/heater unit on most Lay‑Z‑Spa models. Replacement of the sensor harness or complete pump/heater unit is usually required; contact Lay‑Z‑Spa support.
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Repair Difficulty

Hard 4/5

Required Part

Dual Temperature Sensor Harness
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