According to the WSM the engine has to be removed.

I recently thought that my 4.4 might need a new sump gasket when I used an inappropriate sealant replacing the oil pump which would also have required the engine to be removed, but fortunately there aren't any leaks.

Quick update, just changed the oil and seems normal no fragments or anything but did get a small amount of smoke out the exhaust but that sometimes happens on start up anyway. I’m currently letting the oil settle before checking the level. It’s booked into the garage I usually use where the owner has experience of the L323’s. No oil pressure light on at present ! Thanks for all the replies it much appreciated. Anyone know the cost of turbo seal replacement or change as a ball park figure ?

Well I’ve just topped the oil up and took it for a short spin, all seems well and smoke soon disappeared and fingers crossed no issues ! Tempted just to leave it until the garage can check it over. That would mean using an electric mini for a few weeks

Sounds positive. I agree, I would leave it until they can check it. They should be able to check the oil pressure via OBD.

Thanks Ritchie, Wouldn't I be able to check the oil pressure with the GAP ?

I dont believe there is a variable pressure transducer for the oil pressure on the L405 so GAP or any other OBD tool will not help you. I remember GraemeS thread recently on his mission to install a pressure reading device.
The oil light will probably just be an oil switch that operates below a set low oil pressure. 2018 SE SDV8 4.4 Byron Blue

Oh well there you go, apparently not possible. Seems very daft for such an important function.

It just needs a switch to warn the owner of low pressure and anything needing diagnostics needs an accurate calibrated gauge. 2012 TDV8 Vogue (L322)

Your garage should be able to temporarily fit a pressure gauge in place of the pressure switch but they need to make sure that the oil is up to temperature as pressure drops dramatically once the oil is warm. The engines have low hot pressure anyway but it could be useful to check against specs and listen with a stethoscope or long screwdriver for any piston or bearing tapping at idle and low revs. A loose big-end bearing will cause the piston to tap the head on these engines which will be heard long before a bearing rumble.