Freelander 1 td4 engine issue

Hy to everyone,
i have a serius trouble with my freelander.
for some time, when the engine has been running for approximately 10 minutes, the engine light goes on and power drops a lot.
I have done a check with obd2 software but no errore was found although the engine light is on.
I have replaced the fuel filter and the camshaft position sensor (on the advice of a mechanic) but nothing change.
I would be grateful if anyone can help me.
I'm sorry for my bad english, but i'm italian.

If the engine light comes on then there is a code stored that will help you.

OBD2 only works with later 2004 on diesels.
Others need Land Rover specific code readers.

It could be that your turbo boost solenoid is stuck therefore keeping the viens open in the turbo .Check the turbo boost solenoid and the connecting pipes they rot I would advise changing all the rubber vacuum pipes their not dear from the likes of Halfords.

Thank you all for the replies, you are very kind.
Well, the FL has an OBD socket which I used to read the engine values, but even if the engine light is on and the car is in safe mode, the software does not read any errors.
However I once managed to find an old fault code a 0190 code which I think is low fuel pressure sensor.
The strange thing is that the car goes into safe mode only after the engine runs for a while, even when the car is stopped and the engine is idling.
In your experience could it be the fuel pressure sensor?
If it was the diesel pump, would I have to register other malfunctions?
I do not understand anything anymore.
Thank you..

It sounds like the low pressure pump isn't giving enough pressure. If you can rear live values, then check the LP fuel rail is over 340kPa. If it's under 300kPa, then quite often the engine light will come on, but it doesn't always show codes on a generic OBD2 reader.
If the low rail is under 300 kPa you need to replace the LP pump, but only with a Pierburg, and not a cheap ebay one, as they are all pretty much rubbish.