"Stall" means that something usually driven has been stopped - possibly by being loaded up too much. "E15" will be specific to whatever item it is you are talking about.
Unfortunately, not being psychic we can't help any more other than maybe suggesting that you could use a Google search to your advantage.
acp
April 2017
I can answer this question...
Search - mend, repair, fix How to mend E1 Stall Error What That It Mens??
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix gym/fitness equipment.