I have an oil furnace controlled by a digital thermostat it has since strangly started showing 8888 in the display and p1 and p2 plus all other icons are on and won't go away. I rest and replaced the batteries but to no avail what could be the issue?

After a reset, you must reprogram it.

NOMA THM301M User Manual (Page 8 of 8) (http://www.manualslib.com/manual/635782/Noma-Thm301m.html?page=8#manual)
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