Display shows C4 and cooker will not start or aborts cooking.

Safety first: Unplug the cooker and allow it to cool completely.

• Check for steam/moisture intrusion: Remove the lid and inspect the underside, especially around the steam release and anti-block shield. Excessive condensation can migrate into the lid sensor area.
• Dry the lid: Remove the sealing ring and anti-block shield. Hand-wash and dry thoroughly. Let the lid air-dry for several hours, ensuring no trapped moisture around the sensor area.
• Inspect lid connector: On models with a lid connector, ensure it is dry and clean. If any moisture is present, dry gently with a lint-free cloth and allow additional air-drying time.
• Run a water test: Reassemble, add 2–3 cups of water, and run a short Pressure Cook cycle. If C4 reappears immediately, the lid sensor may be shorted and should be replaced.
• Component replacement: Replace the lid temperature sensor assembly or complete lid assembly if the sensor is not separately serviceable. If a new lid/sensor does not resolve the issue, the main control board may be defective.