Display shows Hi or a very high temperature reading; unit may run continuously or shut down with alarm.

Safety: Disconnect power before removing panels.

• Confirm interior temperature: Use a separate thermometer to verify if the cabinet is actually warm or if the reading is false.
• Inspect sensor and harness: Access the cabinet thermistor and check for a broken probe, disconnected plug, or cut wires.
• Test continuity: With the sensor disconnected, measure resistance. An open circuit (OL) indicates a failed sensor. Replace with the correct Monogram thermistor.
• Check connector at control board: Ensure the thermistor harness is fully seated at the main control board and that pins are not bent or corroded.
• Replace control board if needed: If a known-good sensor is installed and wiring is intact but the display still shows Hi, the control board’s sensor input may be defective.

After repair, allow several hours for the temperature to stabilize and verify readings.