Cupra 280 Coolant issue, any help?

Dec 7, 2020
6
0
Hey guys!

I have a problem with my Seat Leon Cupra 280 (2015 - 100k kilometers driven) that started on Thursday on my way home from work.

So far noted issues:
-Coolant liquid temperature is jumping all over the place when driving slow or stopping a lot to lights.
-When starting the car when it is cool it is 90, it does not start from 0 like normal.
-On a highway drive, it keeps quite settle at 90, but can suddenly jump in a matter of seconds to 110 or higher and quickly goes down back to 90.
-If I shut down the car when the temp shows 120 and let it be for 1 hour, it shows still 120 when igniting again...

I called to my local car maintenance company and they told me directly that 99% chance it is thermostat and they said that multiple parts needs to be changed during the change of thermostat (thermostat, thermostat housing, water pump, water pump belt and Antifreeze liquid). And for example to my car the water pump was changed 20 000km ago.

I personally changed the coolant temperature sensor from the front of the car, but it did not help anything and I am wondering that is there more then one sensor? This maintenance the they are suggesting to me is super costly and for me this sounds like a sensor problem.. Or is it really possible that the temperature can jump in a matter of seconds so much and come down so quickly? Plus also the fact that it automatically starts from 90, not 0.

-Hemavol
 
Dec 7, 2020
6
0
1654345479204.png


So based on this picture, there seems to be 2 sensors and I have changed one circled in the picture.

So I have changed radiator outlet coolant temperature sender.
 
Last edited:

mty12345

Active Member
Jun 17, 2011
3,727
450
bristol
I agree with you. For the temp to jump around like that, and especially for it to be on 90C at start up, this definitely sounds like an electrical/sensor issue.

I'm not familiar with the 280, but in earlier cars there were 2 seperate temp sensors, but they were inside one sensor housing (4 pins) One sensor fed data to the ECU, one sensor fed data to the dashboard. Maybe in the 280 they have split it into 2 seperate sensors? I would try to replace the other sensor if not too expensive.

Have you looked at live temperature data from the engine? Most cheap obd2 scanners should be able to do live temp data. See if the data at the ECU/PCM is different from the dashboard.

With the ignition on, but the engine not running, try getting someone to look at the dashboard gauge while you move the wiring about near to the sensor. You may have a loose connection there.


EDIT: After looking at parts for your car, i think they have split the sensors into two seperate sensors. Each sensor has 2 pins, so this would make sense that one feeds the ECU and one feeds your dashboard

Here is the one you changed: (circled in your pic)

And here is the other one I think you need to change.

I hope that helps
 
Last edited:
Dec 7, 2020
6
0
I agree with you. For the temp to jump around like that, and especially for it to be on 90C at start up, this definitely sounds like an electrical/sensor issue.

I'm not familiar with the 280, but in earlier cars there were 2 seperate temp sensors, but they were inside one sensor housing (4 pins) One sensor fed data to the ECU, one sensor fed data to the dashboard. Maybe in the 280 they have split it into 2 seperate sensors? I would try to replace the other sensor if not too expensive.

Have you looked at live temperature data from the engine? Most cheap obd2 scanners should be able to do live temp data. See if the data at the ECU/PCM is different from the dashboard.

With the ignition on, but the engine not running, try getting someone to look at the dashboard gauge while you move the wiring about near to the sensor. You may have a loose connection there.


EDIT: After looking at parts for your car, i think they have split the sensors into two seperate sensors. Each sensor has 2 pins, so this would make sense that one feeds the ECU and one feeds your dashboard

Here is the one you changed: (circled in your pic)

And here is the other one I think you need to change.

I hope that helps
Thank you for your reply. I wish I knew where this second sensor is located or where to look. I am not so good with cars ☹️
 
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