Display shows E4 and the Nuwave air fryer will not heat or stops mid-cycle.

Safety First: Unplug the air fryer and allow it to cool completely. Heating components can remain hot for a long time after use.

Step-by-step checks:

• Visual inspection of heater area: Remove the basket and look up at the heating element. Check for broken coils, heavy carbon buildup, or areas where the element has sagged and touched metal surfaces.
• Check for burning smell: If you noticed a burning plastic or electrical smell before E4 appeared, suspect a shorted element or wiring.
• Access heater wiring: With the unit unplugged and top cover removed, locate the heating element terminals and wiring harness. Look for melted insulation, loose spade connectors, or discoloration.
• Continuity test (advanced): Disconnect at least one heater lead and measure resistance across the heating element with a multimeter. A typical element will show a finite resistance (often 10–40 ohms). A reading of 0 ohms (short) or OL (open) indicates a bad element.
• Check thermal fuse: Many Nuwave models include a thermal fuse in series with the heater. Test it for continuity; if open, it must be replaced with the same temperature and current rating.
• Replace faulty parts: Replace a defective heating element assembly or thermal fuse. If these test good, the heater relay on the main control board may be faulty and the board should be replaced.

Note: Do not bypass thermal fuses or safety devices. They are critical to prevent fire hazards.