wfb2004gb/16 7709 01918

This machine is overheating on the wash phase.

Cleaned loads of scale off the thermstat and thought that would do the job.

Still overheating.

The timer does advance through the cycle but water gets really hot.
The variable temp control does click on and off. If you turn the variable temp control to zero when heating it does turn the heater off.

All wiring and connections are ok.

So I am assuming it leaves me with two choices;

The variable temp control unit or the timer?

Anyone had this fault before on this model?

Thanks in advance.