Error 4 indicates that the thumb throttle may be pressed when the bike powers on. Make sure the throttle is in the correct position and is not stimulated by surrounding parts. The following items can also cause this to happen:
- The LCD is twisted and activates the throttle with its case.
- The thumb throttle is too close to the handle or LCD and is being compressed.
- The throttle is experiencing a problem caused by factors such as moisture or a faulty cable.
- There is an issue with the 4-1 cable.
You can perform a quick test by unscrewing the connector coming from the throttle, as shown here