Manifolds, Decats and all things Lamba

[Jay-ZS+]

Heres a senario for people....

If you have an aftermarket tubular manifold fitted that doesnt have a hole for a lamba to be fitted so it is left unplugged. Then added to this theres a decat fitted with a lamba post cat.

Guess it would over fueling massively but would fitting a MIL kit to either or both sensors help to retify the signals to the ecu?

Basically would a MIL kit work if fit to the precat sensor?