P38 2.5 N reg bmw engine

Just been reading up on start problems for diesel 2.5 rangy. Mine was faultless till xmas eve. went to shops but while out, when I went to start my rangy I noticed the glow plug light did not come on and engine was bugger to start, only just fired up after long cranking. I am reasonably ok at diy maintenance so will get the multimeter out and get checking things. I read in a previous posts that the glow plug start relay is activated by the temp sender on engine block, so if this has failed then no signal to ecu to switch glow plug relay on. What is method to test the temp sender to see if it the cause of problem? I will chech the glow plug relay and contacts, also the glow plug voltages. But it sounds like the starting point is the temp sender.

All advice greatly received.

There is a hot start kit which many of us use. Glows the plugs every time. Makes life easier.

First thing is are you getting power to the glow plugs, if yes check plugs if duff replace with Beru ones nothing else , there is also a fuse in the ecu housing behind the battery check that.

With a hot engine the glow plug light will not come on unless you have a hot start fix fitted then it fools the engine into thinking that its cold and turns on the glow plugs so it could be your hot start fix is faulty.

The sensors in the head, two different colours..
Are a cheap place to start.One
for the ECU and one for the temp gauge, later diesels have a third black one at the rear for extra cooling from the Aircon fans.