Thermostat on the way out?

[John Bishop]

Quick queery guys. Hearse runs fine with no error codes. MPG the same as it always has been. Heating works fine and temp guage on dash is fine when driving.
However even when the engine is up to running temp and I am sitting for any length of time (10 mins) such as waiting to pick the kids up from school the guage drops to zero like when the engine is cold. Everything else is fine. Then when I drive away the guage goes back up to normal.
I assume the guage is on it's way out, am I correct in thinking that?

[John Bishop]

On thinking about it I dont think it will be the thermostat and must be something with the guage

[Handyandy-UK]

Sender fault perhaps ?

[merikiito]

What engine?

[John Bishop]

Z30 Merikiito

[merikiito]

I would say thermostat. Its stuck open, I have found diesel engines cool down when idling unlike petrol which get hotter.

[John Bishop]

It has only started doing it the last 3-4 weeks and the guage does the opposite to what you expect. Engine still stays hot and heaters blast out across the range from cold to hot on all speeds

[Celes]

Most likely nothing is wrong. If I sit with the engine idling especially now that it's colder outside the guage will drop below 80 and even to "0".

[Johnny-B]

Hello!
In which possition usualy is staying temperature gauge? Mine is between 85 and 90, but some time its moving between them! Of course if is doing REGENERATION its on 90!

[sir pingu]

Mine between 85 - 90 degrees.