Water temperature gauge

[Monty4rt]

Hi
Had my R400D for about 4 months, all going well.
Today enjoying the good weather, out for a drive and noticed that the water temperature gauge is acting up, going from just over 40c to normal about 80-90 then back to just above 40c.

My limited diagnosis is limited (mechanical numpty) unplugged and reseated the plug to the back of the gauge and got exactly the same result. Took bonnet off, noticed that I have 2 sorts of senders, one that is at the top and back of the engine seems to go in to water rail with a spade connector, unplugged and cleaned and plugged back in same result. Then there is another sender again back of engine offside with a plug connector, pulled that off, plugged back and got same result.

After googling about it seems that the water temperature senders usually fail, so I will order another one but which sender is it that is the water temperature sender, one with a plug or the one with the spade connector?

Thanks in advance.

[CharlesElliott]

Spade one is the dash one, the one with the 'proper' connector is for the ECU.

[Monty4rt]

Thank you for the reply . Is it usual to replace both senders as part of this fault finding, or just do the sender with the spade connector to the gauge?

As it happens driven the car most the day and it has been working 100%, Sod's law !