In Bosch washers, the E02 (E2) signals that water is not feeding into the machine and a washing cycle cannot be started. Particularly, the system is indicating that the feeding process is taking much more time that the machine is programmed to embrace. It means that either the water pressure in the water supply system is too low, or it is not getting into the machine at all for another reason.
First, you should check the water supply system in your home. Check all valves and taps to see if water is running well. If not, the error has occurred due to factors not related to the machine itself. If water pressure is ok, you should check the washer. It may require professional help.
Make sure the inlet valve is open and there is nothing to stop water from feeding into your washer. If the valve is open, but water is not feeding, check the inlet hose for twists, bends, kinks and clogs. Make sure there are no heavy objects constricting it, and it is connected properly to the machine and the water supply system. Make the hose as straight as possible. If the hose is damaged, replace it. If everything is all right, but the water is still not getting into the machine, check the water inlet strainer: it could have gotten clogged. Disconnect the hose and remove the strainer using a pair of pliers. Be careful, because there may be water in the hose and it may spill out on the floor once the strainer is out. Rinse out the strainer and get debris out of it, if any. Put the strainer back in, reconnect the hose and run a wash cycle.