What does error code E:18 mean and how do I fix it?

Error code E:18 means the drain pump is blocked. You should clean the drain pump and also check and clean the drainage hose on the siphon. To access the pump, turn off the tap, switch off and unplug the appliance, open the service flap, drain residual water via the drain hose, then carefully unscrew and clean the pump cover and housing. (Page 32)