Multiecuscan

I have a problem with my Lancia lybra 2.0 Station wagon, which occurs in winter when outdoor temperature drops below 3 degrees. During the ride and heated engine temperature indicator (engine coolant temperature gauge) on the dashboard suddenly stops working, the dashboard indicator light up "engine error" (or the injection system failure indicator in the manual) and the air conditioner stop blowing hot air, and i feel that the performance of the car drops too . I changed the thermostat and the engine’s water temperature sensor without any success. This problem can sometimes fix itself, but for short time. I have used computer-aided diagnosis and Fiat ecuscan - all show that the problem is the water temperature sensor. As I said, I changed it but no success. This is a big problem when you have to drive in winter without hot air. Can anyone help with any ideas, what could be the problem?.

I really do not know is this story going to help you but I had similar problem with my Alfa Romeo 156, 1.9 JTD. Very similar symptoms! And it always happened to me when winter starts! Sometimes during the ride it stops to work and after some time started to work normally. But I never new when it is going to stop or start! I had luck to find really good electrician and I sow what he was doing so I could use it later. And I must say I really needed!
The problem was in small electronic device called resistor! Resistor on Alfa Romeo 156 is seated below dashboard at passenger side. My one was OK but the connectors were very loose and I had to melt them with "soldering iron" two times! After second time doing it did not have any problems yet! I think last time I was fixing it was more than 18 months ago!