[Mccora]

Hi I'm just hoping to know if adding too much indicator (phenolphthalein) during my sodium carbonate and hydrochloric acid titration would have affected the end point and if so, why?

[marquis]

It takes some titrant to convert the indicator from one colored form to another colored form.  So yes, adding too much indicator will add some error. 

Generally speaking,  indicator error is often  a minor source of error.  Over titration is usually a more common source of error.  YMMV.