My XC70 just started showing a low oil pressure warning message, particularly when going around a corner. Now it does it just sitting.
There is also a code P1238 related to the turbo control valve.

The car is due for an oil change which will be done today and the oil in it now looks a bit thin but doesn't smell burnt.
The battery is showing just over 12 volts but is the original Volvo battery with 150,000 miles. It could be weak and that might be the cause of the low oil pressure message but I don't think a low battery would cause that?
It is possible that the sending unit is bad or a loose connection. Haven't checked that yet.
Anyone have any other ideas?

Check the vacuum lines to the turbo, there are 2 or 3. Make sure they are secure and not cracked on either end.
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My name is Klaus and I am a Volvoholic.

Are you using 10W30 synthetic like the manual calls for? You are using a Mann filter, right?

Smell the oil on the dip stick before doing the oil change. If there is gasoline in it, you could have a different problem.

Do a search for the Pnnnn message on Volvospeed.com, there have been discussions about that.
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My name is Klaus and I am a Volvoholic.