E4 error appears and the unit will not start or stops mid-cycle.

Safety first: Disconnect power before opening the unit. Allow all components to cool.

• Reset and test: Unplug for 10 minutes, then plug in and run at a moderate temperature. If E4 returns quickly, proceed to inspection.
• Check sensor mounting: Access the cooking cavity from the top or rear. Confirm the NTC sensor is firmly clipped in place and not hanging loose or touching the heating element directly.
• Inspect connectors: Trace the sensor wires to the control board and reseat the plug. Look for corrosion, bent pins, or partially inserted connectors.
• Compare temperature: If you have an oven thermometer, run the fryer and compare displayed temperature to actual. Large discrepancies suggest sensor or board calibration issues.
• Replace suspect part: If the sensor is physically damaged or readings are unstable, replace the NTC sensor assembly. If a new sensor does not resolve E4, the control PCB likely needs replacement.