What the meaning E1?

I have a TX2.5xt treadmill, the motor broke down ,,, I make repair with a rebuild one and now when I reconnect the E1 appear on the main sream why ?
What this E1 means ?
Please help me because I really want to continu to use this treadmill and since I pay a lot for the new motor I really want to continu with the TX2.5,
So why the E1 appear on the main sream ?????
Thanks for helping me