I have the fault code F23 on my Siemens washing machine?

it means you have a leak which has collected in the drip pan of the machine and triggered the float switch. Remove back panel and mop out the water . Most likely is a hole in the door rubber, can be very small hole. if cant see it run machine on rinse for a while then drain and remove front clamp ring on door rubber and pull off front edge of rubber and lift bottom edge up to see under, if underside of rubber is wet rubber is holed.

Kenjo
December 2013