Berlingo 2.0 HDI, does not start with low temperatures

Hello,
because, my 2.0 HDI Berlingo (90 hp), does not start in winter.
It is from the year 2002.

In summer it starts well, the first.
In winter, with temperatures below zero it is difficult to start or does not start.
The witness goes out quickly.

Battery: New, less than a year.
Preheating spark plugs: I changed them 1 year ago in the Citroën workshop, at least I hope.
Filters: All new.
Starter engine: works.

Some tell me that it can be:
- Preheating spark plugs
- lack of pressure: low or high pressure pump ???
- The Gasoil anti -back circuit is discharged
- probes
- Starter engine: Little powerful for cold temperatures.
- Gasail that is freely

freezing near Switzerland, so that soon the temperatures go down a lot, up to 20 below zero. Normal in winter is about 5 or 10 below zero in the morning.
The car sleeps in the street.
I do few km. I have the work nearby.
Before I lived in Seville, no problem to start in the morning.

I am very lost with so many more breakdowns.
Someone has had the same problem.
Thank you very much for helping me.

With the tester it measures the snough's rejistors

If before the cold I turned on well if they can be the pre -residue spark plugs or the preheating temperature sensor if you say that the preheater sewer is delayed very little. The way to test if they are the spark plugs is: in the morning a thick cable place it in the positive of the battery and the other point in the spark plugs are at the top of the cylinder head (it is said so in Colombia) it takes about ten seconds you take it away and proceed to turn on the car if you turn on the spark plugs are good looking for damage to the sensor or the timer

Hello Frogoneta, I don't know if I'm wrong, people in Switzerland do not have prepared plugs next to the car park to put an electric blanket in the engine or something? I think your car itself has no problem apart from that of the temperature at which you start it that will be -10 or more ??? Already there you would have problems to start any vehicle even at minor temperatures costs work that continues to work ... a greeting

Thank you as soon as I solve it. My neighbors do not have that electric blanket however they start well even if I do - 10.