I’m not sure I understand. The engine light should come on regardless, whether you’ve got an egr delete or not. Unless of course it never had an engine light in the first place. But you’d need to find out and prove it.
As it’s your front bags leaking you want to be soaking them first, then the air supply lines to them and then if you find nothing from that then the control manifold, but obviously be a bit sensible spraying around that.
Well that’d be a good start really, although I can’t imagine a garage not doing that as soon as they got it onto the shop floor, plug it in and scan it, then road test it depending on what the scan comes up with.