Display shows E3 during preheat or cooking; unit may shut off heating prematurely.

Safety first: Unplug the Klarstein air fryer and let it cool for at least 30 minutes before inspection.

Steps to resolve:

• 1. Check airflow: Ensure the fryer is placed on a hard, flat surface with at least 10 cm clearance around all sides and above. Clear any obstructions from rear and bottom vents. Clean dust and grease from vents with a soft brush.
• 2. Clean internal air path: Remove basket and pan. Clean accumulated grease from the inner cavity, especially around the heater guard and fan intake. Built-up grease can trap heat.
• 3. Inspect thermal cutoff and thermostat: Open the housing. Locate the thermal cutoff (small cylindrical device in series with the heater) and any bimetal thermostat near the heater. Check for discoloration or loose mounting. Ensure they are firmly attached to the metal surface for proper sensing.
• 4. Test thermal cutoff (if accessible): With power disconnected, test continuity across the thermal fuse. If open, it has tripped and must be replaced with the same temperature and current rating specified for Klarstein models.
• 5. Verify sensor placement: Confirm the NTC sensor is correctly positioned in the air stream and not touching the heating element directly, which can cause false high readings. Reposition if necessary.
• 6. Control board check: If airflow is good and safety devices test OK, the control board may be misreading temperature. Inspect for burned components near the sensor input and heater relay. Replace the control PCB if damage is found or if E3 persists with known-good sensor and cutoff.
• 7. Test operation: Reassemble, plug in, and run at a moderate temperature (e.g., 160°C) with an empty basket for 5–10 minutes. Monitor for E3 reoccurrence.

Warning: Never bypass thermal cutoffs or thermostats; they are critical safety components.