Thermostat shows E02 and temperature reading is incorrect or heating locked out

Safety first: Turn off mains power to the thermostat before opening the unit.

Diagnostic steps:

• Remove the thermostat from the wall plate and locate the floor sensor terminals.
• Check that the two sensor wires are not touching each other outside the terminal block and that no copper strands are bridging between terminals.
• With a multimeter set to resistance, measure across the sensor wires. A reading close to 0 Ω indicates a short circuit.
• Inspect the visible length of the sensor cable for damage from screws, nails, or being trapped under trim.
• If the cable is damaged or the sensor reads near 0 Ω, replace the Heatmiser floor sensor with a new one of the same specification.
• After replacement, re-check resistance (should be in the kΩ range), reconnect to the thermostat, restore power, and verify that E02 has cleared and the temperature reading is sensible.

Note: If the cable is buried and cannot be replaced, configure the thermostat to use the internal air sensor only (if the model supports this) and disable floor limit functions.