I believe it is caused by a faulty ground or other wire connection, it started after snow blowing for about an hour and a half, so I think vibration caused a loose connection. Where is the ECU located in the lx3310 w/ a cab? Also, when I do get it started the throttle acts weird unless I disconnect the battery while it is running. My dealer advised me it could be a the battery since it is -15deg F here and the thing was slow cranking. So I purchased a new battery and it cranks and starts now. (awesome) but wont throttle up correctly. So now after some research I believe wiring could be the cause. If someone has had to troubleshoot E-21 where are the connections I need to look at?