Ninja multicooker shows E03 and will not build pressure or complete the program.

Safety first: Ensure the unit is unplugged before manipulating the lid locking mechanism.

• Verify lid orientation: Make sure the Ninja pressure lid is aligned with the lock icons and turned fully to the LOCK position until it clicks.
• Inspect lid locking tabs: Check the plastic or metal locking tabs on the lid and the mating slots on the cooker body for damage, warping, or food buildup. Clean thoroughly with a damp cloth and dry.
• Check lid sensor actuator: On many Ninja models, a small plastic post or tab on the lid engages a microswitch in the housing. Confirm this post is intact and not bent or broken.
• Test with gentle pressure: With the unit plugged in (but not cooking), close and lock the lid while gently pressing down. If E03 clears only when pressing, the lid sensor or hinge alignment may be off.
• Persistent E03: Likely indicates a failed lid detection switch or wiring. This requires disassembly of the upper housing and should be done by a technician.