Did a search, found some threads with a similar issue but no one posted about a solution other than "I will replace X and tell, bye" and then nothing 
So here is the problem :
While driving, engine hot and in working order (80km trip) the coolant needle drops to zero, too fast to be cold water on the sensor (needle reads just a little low than the lowest value, like the instrument was turned off). Radiator fan turns on, engine check light turns on.
After a pair of kilometers the needle suddenly came back to life and working, fan turns off; engine light keeps staying on so there is indeed an error code saved.
Yes, my thermostat has started dying but it's not alterady that bad, just a little slow but keeps the correct temperature (fact is, when the needle started working again, the temperature rose back to normal), I was planning to replace it the next month so the sensor may just join the parts list next to a well deserved engine service (and of course new coolant).
A friend here at work suggested also the map sensor, but the car was running like normal when the issue came up (although I do expect to find an incongruent air temperature warning). The engine is the 1.2 60HP EURO4 - cable throttle - iirc the ecu should be a 4AF, the large aluminum case one next to the battery.
Shame on me, I lost my bluetooth obd scanner so I'm back to old style guesswork until I get another one
Sounds like a water temperature sensor fault to me, the safety/limp strategy -fan immediately switched on- checks out ... but I'm too fond of little fiats electrical issues (and mysteries, ghosts, paradoxes ) so I ask to you if this is a common/known issue that maybe has a more esoteric cause like a bad grounding or an infortunate placing of connectors and so on, just to be sure and eventually check there in advance.
So here is the problem :While driving, engine hot and in working order (80km trip) the coolant needle drops to zero, too fast to be cold water on the sensor (needle reads just a little low than the lowest value, like the instrument was turned off). Radiator fan turns on, engine check light turns on.
After a pair of kilometers the needle suddenly came back to life and working, fan turns off; engine light keeps staying on so there is indeed an error code saved.
Yes, my thermostat has started dying but it's not alterady that bad, just a little slow but keeps the correct temperature (fact is, when the needle started working again, the temperature rose back to normal), I was planning to replace it the next month so the sensor may just join the parts list next to a well deserved engine service (and of course new coolant).
A friend here at work suggested also the map sensor, but the car was running like normal when the issue came up (although I do expect to find an incongruent air temperature warning). The engine is the 1.2 60HP EURO4 - cable throttle - iirc the ecu should be a 4AF, the large aluminum case one next to the battery.
Shame on me, I lost my bluetooth obd scanner so I'm back to old style guesswork until I get another one
Sounds like a water temperature sensor fault to me, the safety/limp strategy -fan immediately switched on- checks out ... but I'm too fond of little fiats electrical issues (and mysteries, ghosts, paradoxes
) so I ask to you if this is a common/known issue that maybe has a more esoteric cause like a bad grounding or an infortunate placing of connectors and so on, just to be sure and eventually check there in advance.
