C10 error is displayed and the Thermomix refuses to start any program involving the lid or measuring cup.

Safety first: Unplug the appliance before inspecting the lid mechanism.

• Clean lid and rim: Remove the lid and thoroughly clean the rim of the bowl and the lid locking area. Food residue can prevent proper engagement of the safety mechanism.
• Check lid orientation: Ensure the lid is correctly positioned and fully closed according to the user manual. Some models require a specific alignment mark.
• Inspect for damage: Look for cracks, broken tabs, or missing magnets in the lid and locking arms. Replace the lid if any mechanical damage is found.
• Sensor check (advanced): With the unit unplugged, remove the upper housing (if you are qualified) and inspect the lid sensor (reed switch or microswitch) and its wiring. Reseat connectors.
• Service recommendation: If the error persists with a new or known-good lid, the lid sensor or main PCB input is likely faulty and should be serviced professionally.