Hmmm, it may not have set a CEL but I’m guessing there would be a pending code in the ECU. Do you have a code reader?No its the centre part of the speedometer saying service engine in orange.
If you’re just free revving the engine in park or neutral you will not make any boost since there is no load.yes I have used a code reader and comes up no codes I also noticed when the engine is reved no turbo pressure.
Found the problem,there is an oil seal problem between the oil pump and strainer pipe which causes low oil pressure {one bar}and causes the low oil pressure show on centre display and also shuts engine into limp mode.Seemingly a common problem and also on same engines in Vauxhall\Opel diesels as well.Car now in workshop to fit new seal.Will reply when fixed.If you’re just free revving the engine in park or neutral you will not make any boost since there is no load.
After owning 3 different NG 9-5’s I’ve noticed they act wonky and do really weird stuff if the battery is even remotely questionable. How old is it? If it’s more than a couple of years old I’d have it checked or replaced. Good time to check and clean battery terminals too. Put it back together and see how it runs.