The error code E24 on Bosch dishwashers is a drain error code although it can be triggered by the circulation pump or main control issue. The first thing to check is your drain system, make sure the filters are not plugged and the check valve is in place. Your check valve is located in the bottom of your tub on the side wall, generally white in color. If those two things are looking good check your drain hose is it kinked or clogged? (Did you just replace your garbage disposal, if you answered yes, remove the plastic plug that comes on the new disposal.)
The next thing to check is your drain pump, when you press cancel can you hear a humming noise? If not you will need to check for power to the drain pump, there should be 120v. If all the items in your drain system test OK and you are still getting the code the next step will require you to remove the dishwasher from the cabinet.
After the dishwasher has been removed from the cabinet you will need to get to the main control on the lower right side. Make sure the breaker is turned off to the dishwasher at this time. Remove the connector with the three grey and three black wires. Your looking for 89 Ohms on the grey wires going to the drain pump, and 14 Ohms across the black wires going to the circulation pump. If those both check out you will need to replaced the main control.
( Just a quick update if your wash motor is not working properly this will also make the code come up. If the brushes in the motor get old this will cause the motor to drag and that's what triggers the error code.) Hope this helps!!!