P38 DSE fuel guage problem

Hi, Just got a 2000 P38 2.5 diesel and all is good except the fuel guage.
I have searched other threads on this subject but can't find any with exactly the same problem.
The tank is empty when the fuel guage reads 1/4. When I ran out I just put fuel in to get to a garage anf fill up. The fuel guage works normally above 1/4 so I am keeping it topped up for the moment.
Now I didn't check the range on the trip computer when I ran out so no idea what it was telling me. Obviously with fuel in it gives me a range.

Now my question is can I rely on the trip readout and just live with the guage or is it all connected? Does the range rely on the same info from the fuel sender as the fuel guage? I do not want to run it dry again to check the range as I read this could damage the cat.

Could it be a dodgy float? if so is this easy or cheap to replace.
Any suggestions greatly appreciated

cheers
Crox

Sender unit in tank is knackered. Only way to correct it is to fit a new pump. Sender is not available separately.

You can reset the trip meter and do a bout 350 mile. To be on the safe side , whilst the fuel pump works leave it , they have a habit of failing so if it works and you can live with the trip meter leave it

Thank you, I'll try and live with it as I don't do long journeys

If I do need to replace it is it an expensive job?

The pump alone oem is £147 plus two hours labour at whatever rate .