Corsa-B.uk - Vauxhall, Opel and Holden Corsa B Owners Club

OK, I have been having a bit of a weird reading on my dashboard for the coolant temperature dial. It works, but it seems to drop fully to cold then back to the correct temperaure every now and again. Once it gets hot enough past a certain stage, it is fine. It does not stay on cold, it does not stay on hot or flap about all over the place. However, I want to replace the unit that controls this dial to try and solve my issue.

I have looked about online, but I am a bit confused. There is talk of a 'coolant temperature gauge sender' and a 'coolant temperature sensor'.

I am correct in thinking that they are two different things, i.e. the gauge sender just sends the signal to the dial on the dash using a thermister, whereas the acual temp sender records the actual temp for the ECU to control the fan etc.

If this is the case, if the dial went completely wrong, it would not affect the cars performace but I would not have a reading on the dash. Is this correct?

If anyone can help with this dilemma, please advise. Cheers.

I should add then when the needle on the dash drops down, it does not shut off, so to speak, as if no sigal is going it slowly goes back down to cold then slowly goes back to the correct temperaure. Once the needle reaches the middle of the dial it has no problem.

Is there any chance this could also be a thermostat problem?

Im not going to lie and say i know what your problem is but if it was me i would try borrowing a set of clocks just to try out.

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It could be the fan kicking in aswell

Thats true. My fan kicks in just under 100 and stops above 90.

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