90 4 stroke

[jprohan]

HELP? My 90 4 stroke is showing the engine warning code that indicates map sensor 2 (3 beeps, pause, 2 beeps). My mechanic told me bad news; there is erosion in the manifold? does that make sense? And the whole engine has to be torn apart to correct? It's all greek to me. Has anyone gone through this? Can I expect similar problems from my other engine? They are both 1997 (warranty, ofcourse, expired) with less than 500 hours.