I have a neff built in dishwasher, which is about 10 years old, and just recently it has been using an excessive amount of salt. Not only that but it sometimes leaves sallty residue
Just check the salt cap is not split and that it is on squarely and is sealing tight, if all this is ok then the salt valve is probably stuck on. Salt valve is on left side of machine bottom of plastic water jacket. If you are not in hard water area you don't need salt.
Kenjo
March 2014
you must live in England,we don't have this bother in Scotland coz our water is very soft we don't need salt,you could have a problem with the water valve that feeds the salt container ,but a machine of this age is not worth spending money on it