Air fryer shows E4 and will not start a cooking cycle.

Safety first: Unplug the unit and let it cool. Do not repeatedly attempt to start the unit if E4 persists.

• Power reset: Unplug for 10 minutes, then plug back in. Sometimes E4 can be latched by a previous overheat event and will clear after a full power reset.
• Inspect for heat damage: Remove the basket and look up toward the heating element. If you see melted plastic, scorched insulation, or deformed metal, discontinue use and seek professional service.
• Access internal sensors (advanced): With the unit unplugged, remove the outer shell to access the heater assembly. Locate the overheat sensor/thermostat (often a small round or rectangular device clamped to the heater housing) and its wiring.
• Check connections: Ensure the sensor leads are firmly attached and not corroded. Reseat connectors on both the sensor and the main control board.
• Test continuity: Using a multimeter, test the overheat thermostat or sensor according to the service spec (typically it should show continuity at room temperature). An open reading indicates a failed device that must be replaced.
• If sensor tests good: The fault may be in the control board's sensor input circuit. Replace the main control board if all sensors and wiring are confirmed good.

Because this fault involves safety devices, replacement with the correct Instant Pot‑specified part is critical.