What is this?

[EclipseGST]

I take it you have a 2g... On a 2g there is a MAP sensor mounted on top of the intake manifold. When you put a 6 bolt motor in a 2g you no longer need the MAP sensor cause there is no spot for it unless you weld one onto the 1g intake manifold or reuse the 2g intake manifold. Not using it shouldnt cause a CEL nor should it effect any performance or driveablility issues.