E4 appears on the display and the unit will not start or stops mid‑cycle.

Safety first: Disconnect from mains. Do not attempt to run the unit again until the fault is identified; risk of electric shock or fire.

• Inspect heater assembly: Remove the top or rear cover to access the heating element. Look for visible damage: broken coils, burn marks, or areas where the element touches metal parts.
• Check wiring: Follow the heater leads from the element to the PCB. Ensure insulation is intact and wires are not pinched or melted against the metal housing. Replace any damaged wires with high‑temperature cable.
• Measure heater resistance: With the unit unplugged and heater disconnected, measure resistance across the element. A very low reading (near 0 Ω) or direct continuity to chassis indicates a shorted element; replace the heating element assembly.
• PCB inspection: Examine the main control PCB for burnt tracks or components near the heater relay or triac. If any damage is visible, replace the PCB.
• Test after repair: Reassemble fully before testing. Never operate the air fryer with covers removed.