Fiat Dino Forum (FDF)

I've checked the guage and it works so I'm guessing it must be the sender on the heads but it looks like there is one on each head. Surely they both can't be defective at the same time. Or am I missing something obvious.

Yes, you are probably not aware of that the left head sender is a switch,
only connecting the engine temperature gauge wire to ground when engine
is dangerously hot. The gauge will then point at the red end of the scale!

The sender in the right head is the "normal" sender for reading the coolant
temperature.

Both theses senders were used in many Alfas, Lancias and Fiats. See the
spare parts catalogue pic below:
Dinoswede

Thank you for your helpful reply. I had a tough job draining the coolant from the block as the drain tap was broken,but got it done eventually and have now removed both senders.
The switch sender didn't change continuity when heated up so that's probably duff,the temperature sender gave a different resistance when heated up but I'm somehow not convinced it's good so I will probably just buy new ones .