Display shows E4 and the cooker will not build pressure or start the selected program.

Safety first: Unplug the multicooker and ensure it is completely cool before inspecting the lid.

• Inspect the lid interior: Remove the inner lid (if removable) and check for a small sensor or metal probe embedded in the lid assembly. Clean any food residue or moisture around it with a soft cloth.
• Check the lid cable (if applicable): Some Nesco multicookers have a flexible cable or contact pins between the lid and body. Inspect for bent pins, corrosion, or broken insulation. Gently straighten bent pins and clean contacts with a dry cotton swab.
• Reseat connectors: If the lid has a detachable connector, unplug and replug it firmly to ensure good contact.
• Internal check (advanced): With the unit unplugged, remove the top or side cover (depending on model design) to trace the lid sensor wires to the control PCB. Confirm the connector is fully seated and wires are intact.
• Test operation: Reassemble the lid components, plug in the cooker, and run a low-temperature program (like warm or slow cook) to see if E4 clears. If the error persists, the lid sensor or control board likely needs replacement.

Warning: Do not operate the cooker with the lid sensor disconnected or bypassed. This can disable important safety functions.