New problem !!! (solved: Faulty CCV tube)

[TriX5]

Hope you're having a great fourth!

The E70! If it isn't one thing, it's another :-( As reported previously, replaced the MAP sensor in the inlet manifold and the engine limp home message disappeared. However, my wife took it out for a longer run and came back with the CEL on. I reset it and drove it the next day for ten miles. The CEL stays off until a hot restart. Then the CEL comes on but INPA reports that the errors are not actually ongoing. Fault codes are:

P2457which is insufficient effectiveness EGR cooler, faulty bypass valve or insufficient capacity.
4C83 exhaust pressure before turbine implausible
4990 exhaust pressure before turbine implausible
4729 NOx sensor after Denox kat performance or range problem (oxygen concentration too low on overrun)

A little tough to troubleshoot if the issue only happens with hot engine and the CEL turns on but there is no ongoing fault. I am about to pull the intake manifold to replace the vac lines (and replace the IM seals) but I'd like to know if anyone here has had these codes and what the issue was. Last time I had a hot restart CEL, it was the EGR-cooler spring. Looked in there and the spring seems fine but not sure until I get the fan out.

Thoughts anyone? Would it help to run ISTA-D? If so, which subsystem?


EDIT: I can see that this topic is one well rehearsed on various forums. Looks like a vac leak could be the cause for this, might as well dig in to the vac lines and pray it solves this issue as well.