If you have a hub drive motor and are experiencing an error code 08, error code 30, or have inconsistent assist from the motor its good to check the main motor plug for damage and to ensure that its properly seated.
Find the motor plug located on the right side stay. It is above the chain. See red square in the image below.
Disconnect the plug by pulling apart (no twisting). You may have to cut a ziptie on one or both ends of the plug to do so.
Inspect both sides of the plug for any damage or discoloration.
Inspect the wire harness for any damage. Specifically look at the area where the wire comes out of the end of the axle (circled in the picture above). You have to lift the rubber boot off the axle nut to see the area. Look for cuts in the insulation that would expose little thing wires inside. Replace parts as necessary.
Align the arrows on the outside of the main motor plugs and re seat the connector. If you cut any zipties put new ones on to secure the wire.
Power on the bicycle display, did the error code go away?