Hi,
We had a water main get broken in our neighbourhood which left us with brown water for two days. This we think led to grit or dirt getting into the dishwasher as we had the same error code E4 which in the manual states that the filter may be blocked. However on the page before it also says that the water level is too high.
So not being able to find answers on the web, I decided to have a go myself and this is what I did to our MTT4W dishwasher that cured the problem: -
a) UNPLUG THE MACHINE!
b) I removed the outer panel to access the workings of the machine.
c) There is a grey chamber on the right hand side (as you look at the front) which is a float chamber with a plunger. When empty, the plunger is down and the top switch on. It has two switches, the top one allows the water to flow in and when the plunger rises to a certain point, the switch goes off which should cut of the water flow. If the water keeps filling, it activates the second switch which triggers the E4 error code as there is too much water in the machine. It then drains the water and halts the cycle. I took the top off the float chamber and found it too be full of gunk. Cleaned this out and reassembled.
d) I then undid the water inlet solenoid at the back bottom right corner of the machine (I didn't take off the pipe attached on the inside of the machine) and blew through it to dislodge any debris. Re-attached this and tried a cycle.
It appeared to go longer before the error E4 but it still came back. I decided that the only thing left (before dismantling the whole machine) was that the water solenoid was either defective or had debris inside it. This meant either replacing it or giving it a few sharp taps. I opted for a few sharp taps and lo and behold, it now runs without the error. Have completed 4 cycles (programs 2, 3 and 4 twice).
So, It may have been a combination of all of the above or just tapping the water solenoid.
I'm not an engineer, I just like taking this to bits. The above worked for me but I can't guarantee that it will work for anyone else. It may just have flushed any dirt out with the constant attempts at running a cycle.
Good luck
Doug, October 2010