Honestly I have no idea, I don't know much about cars. but thanks for the info I'll start by fitting in a new EGR valve :)

When I briefly ran a Honda Accord recently, it had a check engine light and an "insufficient EGR flow" error code.

It also had what looked like a brand new EGR valve, which was very clean internally and seemed to operate correctly.

Its cleanliness was not surprising, since the EGR plumbing was completely plugged with oil-bound soot, and almost certainly was when the new EGR valve was fitted.

I wouldn't assume that your EGR valve is faulty without checking it.

If I had an "error code diagnosed which said I had a leaking intake system". I would at least consider the possibility that I in fact had a leaking intake system, which would cause the engine to run lean. This might show up in the fuel trims, as the engine management adds fuel to compensate.

Leaks can be hard to find. Methods include running a flammable gas (unlit blowtorch) around the intake plumbing and listening for the change in engine note, or using a smoke machine, the latter probably a "professional" approach unless you are good at improvising.