My treadmill runs for 9 secons and stops and shows E1

Speed Sensor fault.
There is no signal returning to the Console from the lower board.
Check Speed Sensor connection on the lower board.
Check lower board to console connection, and wire for breaks.
Adjust Speed Sensor position.
Replace Speed Sensor.

Ok. So the first thing to try is to calibrate the speed.
You do this by doing the following:

• With the SAFETY KEY in place, hold the ELEVATION UP and SPEED DOWN buttons for five seconds. The console will beep twice, "ENG0" will appear in the Distance window, and a number will appear in the Elevation window.
• Press SELECT until "ENG3" appears; this is for Auto-Calibration.
• Press START to Auto-Calibrate.
• The treadmill will calibrate minimum and maximum speed, and minimum and maximum elevation. When Auto-Calibration is complete, the treadmill will reset to User's start screen. This process takes three to five minutes.

Make sure there are no errors. . .and that the speed goes from super slow to super fast and then stops. . .. if it stays slow. . or stays fast. .or error code appears during calibration, there is a problem.
If after a good calibration sequence, if it still does the stopping and E-1 after 10 seconds. ., then you need to (Power off and disconnect treadmill). . .then unplug the speed sensor from the lower power board, blow into the connector on the wire, and add a little contact cleaner spray to the connector on the board.
Recap: If it actually runs. . .but stops after a few seconds. . but the calibration runs and passes fine. .. .more than likely it is a speed sensor misread or a faulty speed sensor.