We were getting an E4 but now we get an E2 but

I do know that the owners manual should show you what each and every code means? Some times the manufacture will paste a strip located on the panel of the indoor unit showing what each code means. If not, I would contact the factory on this. I know on Bryant, Mitsubishi splits, Day and night, (Bryants), Tranes, Lennox and most all others, do show in the manual and on the unit behind the panel. Try looking for them there.
Sincerely, shastalaker7