I am Tech Mike,
It is a fault with the thermistor, which is just a thermostat that works on electrical resistance rather than a bi-metal strip. The thermistor is usually (on indesit machines- some machine have thermistors attached to the drum) an integral part of the heater element. The fault could be in the thermistor itself, which would require a new heater element. It could be a loose or broken wire or it could be a fault on the PCB (printed circuit board- the ‘brains’ of the appliance). You could check for broken or loose wires (after disconnecting the machine from the mains!) and possibly rectify this yourself- if you are confident AND competent. Otherwise you should be calling an engineer to correctly diagnose where the problem lies.
If you would like to fix this yourself with my continued help please let me know.
The best place to get that part is : http://www.ransomspares.co.uk/
Its best to call them to place this order for many reasons, two big ones, one they will send it out today, and two you wll be sure to get the correct part ;-)
In any case, I will stick with you until this is complete.
Please rate my service kindly.
Also it is the only way I am credited for my time and expertise with you.
Once you rate, I will be notified and will add your question to my priority list so you can reach me anytime until this problem is solved.
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Thank you and have a great day!