DIAGNOSIS Error C6 is a temperature sensor fault. It usually means the inner pot isn't making proper contact with the heating element, either because the pot isn't in correctly or there's something on the bottom.
FIX Unplug the cooker. Take out the stainless steel inner pot. Check its underside and the heating plate inside the base for any food residue or water. Dry everything thoroughly. Place the inner pot back in, making sure it's sitting flat and rotated so it's not catching on anything. Plug it back in.
IF THAT DIDN'T WORK The issue might be a faulty sensor connection internally. Try a hard reset: unplug the unit, wait 5 minutes, then plug it back in. If C6 persists, the sensor itself is likely faulty.
HEADS UP Never run the cooker without the inner pot in place. That can damage the heating element and trigger sensor errors. Also, avoid using third-party or dented inner pots.