Freelander 2 Engine in limp mode

Hi, i have a 2009 Freelander 2S, TD4.
Currently sitting with an issue where the car continues to go into Engine Reduced Speed mode.

Started when fuel gauge wasnt working properly, so broke down without diesel 3x. Had to put diesel in and prime to get started again.
Eventually changed fuel tank and sensor- still now got gauge problems but now car continues to go into limp mode.

When i accelerate goes into Engine reduced mode- no other error messages appear- just says engine reduced mode and then can drive but in limp slow mode.

Problem started about same time i was being stuck without fuel due to faulty gauge.

At a loss- any suggestions please.
Have checked fuel pump and works 100%

Could it be pressure regulator relief valve or maybe a faulty sensor on the fuel rail?

I'd get yourself a ODBII code scanner and read the codes.

It'll tell you why it went into reduced power mode.

When was the fuel filter last changed? also you do have enough fuel in the tank yes, do a battery reset for about 30 minutes, see what happens.

Get some diagnosis on it if that does not work.