E7 displayed, alarm sounds, temperature reading may be unrealistic (e.g. -88°C or +88°C)

Safety: Unplug the freezer before testing sensors or boards.

• Confirm actual temperature: Place a separate freezer thermometer inside to verify real cabinet temperature versus the displayed value.
• Check recent repairs: If a sensor was recently replaced, verify that a correct Montpellier-compatible NTC with the right resistance curve was installed. Replace with the correct part if uncertain.
• Inspect wiring for shorts: Follow sensor harnesses (cabinet, evaporator, ambient) and look for points where insulation may be rubbed through and touching metal. Repair or reroute as needed.
• Test all sensors: Disconnect each sensor from the PCB and measure resistance at known temperatures (room and ice water). Replace any that are out of expected range.
• Reset control: After corrections, leave the freezer unplugged for 10 minutes, then reconnect to clear transient errors.

If E7 remains and all sensors and wiring are confirmed good, the main control board may have a firmware or ADC fault and will likely need replacement by a service technician.