I was recently on my way down the motorway. When my engine for no reason cut out! I coasted to the hard shoulder the switched off the ignition. It started no problem straight after? I drove it 1/2 mile down the road then cut out again!
When I got the car towed home. I started the engine and within no time the cooling fan started up?
A friend mentioned that it could be the ECU temperature sensor sending the wrong message to the ECU? But why would the engine cut out?

Can anyone help?

The diesel lump is a big piece of metal, and holds it heat for quite some time, so the fan coming on "within no time" might not mean anything. The phrase "within no time" is quite subjective, do you mean seconds, minutes or tens of minutes?

Did the MIL come on, any stored error codes?

Blocked fuel filter? (when was it last changed). How many miles have you gone since your last fill up?

The fan came on after about 5 minutes of the car ticking over. The fuel tank was full and so was the car as we were going on holiday at the time. The filter was changed about 4000 miles ago it's had a new turbo, DPF, and service.

So are you saying you had just fuilled up? and within 10 miles(?) you experienced the stalling?

Prior to filling up how empty was the tank?

Have you drained some fuel out of the bootom of the filter, filter may be filled with water, and some of this got into the engine.

You didn't mention any stored error codes (use the dash trick if you don't have a code reader).

Misfuelled it?

I had done about 15 miles since fill up, no error codes appeared as I checked with my fault code reader. The AA man said it could be temperature controled problem but rulled out crankshaft sensor because the rev counter droped with the speed as the car cut out.
And as for missfueled???
Where would I find the ECU temperature sensor (not the dash temp sensor)?