Engine Light 1999 Honda Accord Courpe

What must be done when the engine light comes on 70k miles, I periodically changed the oil, all filter on a regular basis

Check engine light or maint/ req'd light?

CEL - take it to a dealer or shop to pull the codes.

You should do more maintenance then oil/filter change. Suggest picking up a maint/ schedule from any Honda dealer in your area.

This is not a tech. section.

Don't skip a timing belt replacement.