How to resolve Anti flood warning on built-in AEG Favorit 55402 VI?

I have a built in dishwasher that I rarely use because I live on my own. The flat itself less than a year old and in that time I've used the dishwasher about 10 times.

About five minutes into a cycle this evening the machine started beeping and showing the -30 message, which I read in the manual is a warning about the anti-flood drainage system.

Many people have posted advice on tipping the machine and allowing water to pour out to resolve the problem. My issue is that the appliance is built into the kitchen and therefore cannot be tipped.

If you have any advice please let me know. I'm going abroad for a fortnight in a few days time and want to make sure it is sorted before then.