Miele G5720SC dishwasher Fault F78

[chris5500]

Hi
I have a Miele G5720SC dishwasher which is just under 3 years old. So far the heater element has burnt out and been replaced 3 times (twice under warranty, the 3rd time I had to pay £117 call out).
Now it has developed another fault and randomly aborts the wash displaying Fault F78. Miele say it’s a circulation problem and needs an engineer visit.
I tried swapping the pump with one of the old motors that were replaced but made no difference. All connections to the motor etc look OK.
The fault doesn’t occur on a Quick wash or the pre-wash part of a full sensor wash but appears to be random after that – sometimes before the tablet has dissolved others well into the wash - maybe even a rinse cycle.

I’m reluctant to pay Miele any more money – especially as the element will probably fail again in a few months, so anybody any thoughts what else to check?

Thanks
Chris.

 

[RichardMNZ]

I had a Miele washing machine which chewed TWO heating elements. The issue was not the element. In my case it was the PCB.
In my machine there was corrosion on the PCB which affected the sensing of the water level. This was an intermittent problem and the element would burn out when the machine "thought" it had enough water (in one case I observed it was bone dry) and went into washing with the heater element on.

I would check the heater pressure sensor (which senses the water level) and the pcb for corrosion.

Did the Miele person change the element twice and say nothing. Did they not wonder why it burnt out twice?

 

[chris5500]

Hi Richard
Thanks for the advice.
I checked the PCB and that looks OK. The pressure switch is part of the pump unit on this so I put an old one back on but no different!

The first Miele engineer thought there was a problem with the element coating and this had been improved. The other two had no idea why it should keep going and just changed it and went.

 

[RichardMNZ]

Fault code F78: Circulation pump fault.

Connection between the electronic module and circulation pump open-circuited.
OR
Faulty circulation pump (low or excess voltage, blockage, etc.).
OR
Frequency converter electronic module defective.