problems with treadmill pro active iftness cardio trainer +?

The Model is a pro active fitness cardo-trainer+

This machine has not been used on a regular basis. However, just recently it has been used more, maybe two or three times a week.

The error message first appeared when I was running on the machine and it reached 8 kilometres. The message read E1.

The machines is approximately 1 year old.

I have read that the problem could be with runnning the machine through an extention cable. My machine is run through an extention but I have checked the extention cable and it works fine for everything else?
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> Hope you can help.