Boost leak CM870......check engine light?

[snailexpress]

(08-08-2017 )Rawze Wrote:  Unfortunately ISX engine will not usually throw CEL for low boost unless it is so severe it will not make any.

In this case it highly possible. The ECM commanded EGR valve to open to mix more exhaust in the intake to keep temperature down. But exhaust (EGR part) escapes out before intake manifold.