Very Strange Coolant Temperature Readings

[mark.pt]

I have noticed the coolant temperature gauge has been going to 90c then falling to 60c and then back up again.

The temperature will fall when I'm crusing at speed with low revs to 60c (motorway driving), then rise to 90c when stationary or driving around town (i.e. constantly accelarating / slowing down)

I decided to compare the reading on the climate screen option 51 and found they were different.

Example of figures today:

Car from cold this morning
27 on digital (this can also vary, and has been 3 / 15 etc in the past)
dial low

Both climbed at similar rates to 90c

Digital display would show 90 constantly, but normal dial would change between 60c and 90c.

I also noticed the digital reading would stay at the original figure of 27 and would only change when I turned the fan on.

Decided to replace the CTS with a new green top one today and I still have the same problem.

Next step would be the thermostat, but can anyone explain why there is a difference between the 2 readings.

 

[LEE69]

My climate control always read 90 and that was with the temp gauge not moved, no idea why.
New thermostat as you said will cure it, mines just been done for the same reason, then mine wouldn't hold temp at all.

 

[mark.pt]

My climate control always read 90 and that was with the temp gauge not moved, no idea why.
New thermostat as you said will cure it, mines just been done for the same reason, then mine wouldn't hold temp at all.

Do you mean wont get up to temperature ??

 

[LEE69]

yeah my dash needle never moved of rest, was bloody freezing till it was done lol

Ah just re-read it i meant mine wouldn't hold temp before the change, i blame the magners

 

[mark.pt]

Are you still getting different readings on the dial and digital display since the thermostat was changed ?

 

[LEE69]

No all spot on at 90 now.

 

[mark.pt]

Any more ideas why the 2 gauges are so far out ??

 

[greesha]

Mine does that as well. I'm changing thermostat tomorrow.

 

[mark.pt]

Mine does that as well. I'm changing thermostat tomorrow.

Can you please let me know if this cures any of the problems.

 

[mark.pt]

Mine does that as well. I'm changing thermostat tomorrow.

Did the thermostat change solve the problem ?

 

[greesha]

Oh sorry.


Yes it did solve it. It constant 90 deg in just few minutes

 

[Ricardo]

Mine is dropping from 90 when I am driving fast on the M1 and going down half way to the first mark. When I slow up/get court in traffic it goes up again and sticks to ninety. Sorry to ask what may be a daft question but does that mean my thermostat could be dodgey as well? The cold air over the engine I gather is causing the drop on the dial?

 

[adam cupra 20vt]

Mine is dropping from 90 when I am driving fast on the M1 and going down half way to the first mark. When I slow up/get court in traffic it goes up again and sticks to ninety. Sorry to ask what may be a daft question but does that mean my thermostat could be dodgey as well? The cold air over the engine I gather is causing the drop on the dial?

I would say thermostat I had same problem just before christmas.

 

[mini]

iv had the same problen wid temp gage ,(read my thread) an i had the temp sender AND the thermostat replaced also had the coolant liquid changed too, an touch wood temp gauge sits at 90 constant wen engine warm.hope this helps.

 

[mini]

lol it was adam cupra that pointed me in the rite direction. cheers adam

 

[adam cupra 20vt]

lol it was adam cupra that pointed me in the rite direction. cheers adam

Glad you got it sorted

 

[Moffat]

I don't think the heaters in my Leon are nearly as good as they were in my Astra i had previous. Even when up to full temperature, i'm just not fully impressed with them. Anything that could cause them to not be as hot as i'm used to?

 

[LEE69]

I can't hold my hand over my centre vent if they are on high.
The gauge is sitting at 90 i presume?

 

[mark.pt]

Should be getting the thermostat changed this weekend so I will report once work is completed.

 

[Moffat]

well, the gauge is slightly dodgy. i need to try a new temp sensor. but even when the car's been runing hours, it still doesn't seem that hot.