Thanks for all the comments on repairing the C3 overflow error. I have cleaned out all pipes and the water unit - but my overflow pipe at the bottom continues to release at least 200ml of water very cycle.
It is not a leaking pipe - I placed the overflow pipe in a dish on the side to isolate it from any other possible leaks. What other issue could cause constant water overflow from this tube at the base?

Andrew Gossman, April 2015