Hello, if you go to Isinwheel.com and find the page selling your bike, at the bottom, under specifications, you will find a download for your manual. They are saying error code 03 is a hall sensor. You are saying you have lost your lights. The internet is saying, possibly a throttle plug. If I were you, I would go over each and every plug on you bike (make sure to line up the arrows correctly) to check that they are plugged in properly. Especially check your motor plug. You can also find your controller and check the plugs there. I'm guessing, at the controller your light plug will be one of the smaller ones. Documentation for this bike is going to be very sketchy, so start with this and see what happens.