Mercedes R Klasse diesel intake manifold issue

A scorched intake manifold is a plausible cause for those symptoms on the R Klasse. Have you checked manifold pressure readings? A gasket leak could cause similar behavior, leading to engine performance issues and triggering the check engine light.

I haven't checked the manifold pressure specifically. Is a gasket leak common with these manifolds?

Gasket failure isn't unusual, but scorching of the manifold itself is also a known weakness. The error codes you are seeing likely point to a manifold problem. I'd advise taking it to a workshop for diagnosis.

The workshop confirmed the intake manifold is defective and estimated 1180€ to replace it. This aligns with what I suspected.