I've done a lot of searching and there seems to be an array of potential causes dependant on specific things. I'm hoping someone is able to help piece together what I have and have done to check:

P006A - Manifold absolute pressure - mass or volume air flow correlation
P1247 - Turbo charger boost pressure low

Some point towards inlet manifold cover (replaced 4 years ago), EGR leak?, Turbo feed pipe? Turbo bypass valve? (Looks ok), exhaust manifold crossover?

When I rev up to 2-3k rpm and drop off throttle theres a loud hiss and very small puff of very light white smoke coming from somewhere around or below he passenger side EGR/fuel rail area.

It seems like an obvious leak but not sure what exactly?

Any help would be great as this could be the final straw and the end of her....

Usually a manifold. Lift the engine cover and look for oil staining on the underside of the cover, or the manifolds themselves

Hey Mikey,

Thanks for the response but it seems like it's lower than the manifold cover. It's also just very faint white smoke rather than splats of oil. The covers look clean and I can't see cracks (I know they could be hairline). Both manifold covers have already been replaced (I know they could be gone again).

Would a crack in the manifold cause the turbo pressure fault? I understand the manifold fault but not the turbo one?

I know it's hard to diagnose and it looks like it could be lots of things. It looks and sounds like EGR cooler or 'secondary'?? turbo?

I've got videos if I can find a way to share them - I've also added a photo of the live reading of mass air flow sensor mismatch if that means anything?

https://www.dropbox.com/scl/fi/3j081i1rtpv...g&dl=0

https://www.dropbox.com/scl/fi/r2n9ibmxek9...1&dl=0

The smoke is barely visible but you can see a slight cloudyness after revving around the EGR/fuel rail area

Good news is, looks like it's already had a manifold

Teach me not to read the full post

Bad news is, looks like it's an EGR pipe or crossover pipe that's split. Presumably, the smoke smells like exhaust fumes?
Less likely is one of the boost hoses off the turbo, I've never seen one of them split

So bad news as in it's expensive?

I've done a lot of work on it myself so happy to get dirty with almost anything. I read the crossover pipe is a nightmare.

What would you suggest as next course of action? Smoke test? Trial and error on replacement parts?

I'm at the point now where enough is enough but if there's one last hurrah I might go for it. Even if I trade in at this rate I ideally need it functional

Have a look for any soot deposits around the heatshields and bell housing