how to fix it.
1999 Honda accord with2.3l has code p1491 egr vavle lift insufficient detected. on 1998 Honda Accord
The simple way to look at this is the computer is wanting more fuel to enrich the fuel mixture. Demanding enrichment from the EGR for help does not satisfy the demand, so sometimes it blames the EGR for the fault and gives an EGR fault code. Now in mentioning this, it does not mean the EGR is the problem. This is a way to explain to someone who doesn't know the operating systems to be able to kinda understand some basics. It would be better to have this system diagnosed by a qualified technician, before you start spending money for unnecessary parts chasing a fault, without understanding the reason for the fault, and not have the instruments to find it. In My Opinion.
Test egr valve , make sure it's getting proper signal.