If you see a “check engine” light, or the bike wont engage assist or throttle,  here are some things to check.

Follow the wires from the throttle and brake interrupt switches down the handlebar and into the braided wire harness.  Look carefully to make sure the connectors are coupled together firmly.  You may have to strip back the braided loom to see them easily and re-connect them

Flick the brake levers several times,  some grit may be in the brake switches causing the “brake” indicator to illuminate on the dash. 

Remove the battery, wait 10 seconds, then re-install the battery and power the bike up.  The display and controller are like any computer, they like a clean re-boot. 

If you see an error code on the display,  eg E01,  E08, E09 etc.  best to phone 1-800-661-9653 for suggestions, or consult the display manual supplied with the bike.  It will indicate what area is causing the code.

If you still see a check engine light, or you have an intermittent check engine light,  you may have a loose connection in the harness. SEE THE PICTURE ABOVE.  Pull the battery.   Then remove the top battery mount out of the bike.  The controller is above the top battery mount inside the frame.  Carefully pull the controller and wiring down out of the frame.  Inspect each wire connector to ensure all the pins and receptors are firmly pressed into the connectors.  You can do this by gently pulling on the wire side of the pins, to see if they pull out.   If you find one that has pulled out,  you will notice a small tang on the edge of the pin.  Prise this tang out slightly, and re-install the pin, until you hear a good “click”.  Pull on the wire to ensure a good tight fit, then re-connect the connectors.  You should be good to go.