This article is for error codes for dishwashers bought from John Lewis (example model number JLBIDW1200) which were manufactured by NEFF. These error codes may be used on other Neff dishwashers as it’s unlikely the John Lewis appliances are fundamentally different. If 30 appears in the display (red LED) it means that the anti flood device has activated.
The instruction book simply advises to call an engineer, which is probably the best course of action. What this fault code means is that the dishwasher is leaking (or at least a device to detect leaks has triggered). In the base of a dishwasher there is usually a micro switch and float mechanism, which activates if water gets into the base.
Finding a leak
Finding a leak in a dishwasher can prove difficult. The trouble with dishwashers is that they are very difficult to work on. There’s no back panel to take off so you can’t have a quick look inside. There is a lid to take off but it only reveals a sealed stainless steel tank and a few hoses. It might be worth a quick look in case you can see evidence of a leak. But trust me, dishwashers are very difficult to work on. Even as a very experienced appliance engineer I used to hate working on them. In the end I decided to stop repairing them because I worked for myself – and I could.
Other than that, in order to get to see inside the base of the dishwasher you would need to start stripping it down. With many dishwashers you need to take off the lid, remove the kick strip at the front, then remove both the side panels in order to be able to see the parts that are mostly crammed underneath in a space no higher than 6 inches.
So basically, the chances are there is water in the base of the dishwasher caused by something leaking. Unless prepared to strip it down to investigate book an engineer