When was the water pump last done?
The coolant temp sensor won't stop it warning up, it's more likely a mechanical problem, BUT it might stop the fan cutting in, as you said tho, the fan won't stop it warming up, and like lee says, it will over heat/ go above 90/95 degrees if its at fault...

If it was plugged in to, the scanner should read the ecu's reading of coolant temp, if its different to the gauge, it's faulty...
 
When was the water pump last done?
The coolant temp sensor won't stop it warning up, it's more likely a mechanical problem, BUT it might stop the fan cutting in, as you said tho, the fan won't stop it warming up, and like lee says, it will over heat/ go above 90/95 degrees if its at fault...

If it was plugged in to, the scanner should read the ecu's reading of coolant temp, if its different to the gauge, it's faulty...

Lets start again.

1.) Cam belt/Water pump done by seat @ 75k less than 2 years ago (Car is on 102k now)

2.) Coolant temp sensor was changed as VCDS were showing it as a fault & temp gauge would sometimes drop down to 0 and back to 90 on motorway driving. @ (101k)

3.) Cant remember that the temp sensor was working perfectly, as the issue started a few days after change.

4.) Temp reading settings on VCDS

- 001 Engine temp 53c
- Climate control unit address 51, showing 53c
- 17 i think (instruments) showing coolant temp 73c
- Car gauge showing 70-75c

All measured same time.....


My assumption is that the sensor is giving a faulty reading to the ecu as this has started after the change.

- Other things i could think of is seat not changing the stat.... i daubt they're at this level
- I think there is no link with the fan as it is clearly nonsense which is trying to empty my pocket
- seat also think it could be a faulty gauge, which i dont believe as it would also show on vcds / and dont see why it would suddenly become faulty after changing the coolant sensor.

-Lastly, water pump, after 25-30k? + wouldn't it be overheating?



Im thinking of draining the system, changing the sensor for a new one, refill, and run through to eliminate any chance of an airlock, as apparently, SEAT didn't fully drain the system but bled it...?

Id also say that the fuel consumption has dropped from around 390 miles until reserve to 370 ( but i think this is the winter season thing )

Any thoughts on what hasn't been covered?
 
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I agree mate. The sensor should be within less than 5 degrees, (ideally same)

(Mine was 20-30 difference
(before changed)

if its showing 20+ difference, it should be the sensor at fault, possibly gauge, but I would have thought vcds will pick it up, can you test it in actuators? Sometimes (Renault I know it does) you can find a way of getting the needles to all move around to see if they respond correctly I've never used vcds, so I'm afraid I'm not sure what it does/nt do...:/

Seat are unlikely to lie about the stat,

Pump should live at least 5-10 years

Seat probably didn't drain it completely, they would just pull refill (hopefully bleed) when finished


Other long shot, maybe a blockage,
but I would try a genuine ect sensor first, as you say the problem started after changing it last time,,,
Sorry if i asked for same info again mate, I didn't think to go back to first page...
 
I agree mate. The sensor should be within less than 5 degrees, (ideally same)

(Mine was 20-30 difference
(before changed)

if its showing 20+ difference, it should be the sensor at fault, possibly gauge, but I would have thought vcds will pick it up, can you test it in actuators? Sometimes (Renault I know it does) you can find a way of getting the needles to all move around to see if they respond correctly I've never used vcds, so I'm afraid I'm not sure what it does/nt do...:/

Seat are unlikely to lie about the stat,

Pump should live at least 5-10 years

Seat probably didn't drain it completely, they would just pull refill (hopefully bleed) when finished


Other long shot, maybe a blockage,
but I would try a genuine ect sensor first, as you say the problem started after changing it last time,,,
Sorry if i asked for same info again mate, I didn't think to go back to first page...


Haha no.no mate, there was no annoyance, I just wanted to make sure everything is listed in one reply, as its all spread over within this thread.

I don't know what you mean by aculators... Can you explain?

I didn't see any signs of work, but not totally sure where exactly it is, I've seen a thread step by step for the thermostat but I don't remember where it is now lol. If someone could link again would be great.

I don't understand if there are two sensors of such telling me the temp of the engine, and seperatly telling the coolant temp.
as I said, 001 engine showed 53c.
17 instrument cluster showed 65-75c. As coolest temp, don't remember exact fig

I will probably go with the sensor when the weather gets better. And also refill the system to check for the airlocks... + that's the cheapest option lol

if that doesn't work, I will give up and probably go to a decent local garage where I can be present during the work/diagnostics

Anyway, further ideas and device are very very welcome, this is proving very helpful... Keep them coming
 
Haha no.no mate, there was no annoyance, I just wanted to make sure everything is listed in one reply, as its all spread over within this thread.

I don't know what you mean by aculators... Can you explain?

In vag com, you should be able to operate certain components on the car, like heater fan, radiator fan, boost control solenoid, and hopefully the temp gauge, then you watch/ listen for life forms

I didn't see any signs of work, but not totally sure where exactly it is, I've seen a thread step by step for the thermostat but I don't remember where it is now lol. If someone could link again would be great.

Thermostat=behind alternator,
Two bolts and coolant hose go into it,

To remove... Disconnect battery earth lead,
Take tension out of alternator belt, easiest way is pull the belt and find a pin/Allen key to fit in the hole in the tensioner to lock it, note the belt route
Remove belt
Undo two 13mm bolts holding alternator, gently lever away from engine, slide out the way, or remove completely if preferred
Undo two bolts revealed behind alternator, pull out thermostat stat, and rubber seal, job done:) well, half, just re assemble on reverse...:)

If u want to test stat: boil a kettle, and pour water in a mug with the thermostat and see if it opens up. Or, boil in a saucepan with thermometer and see exactly what temp it opens.


I don't understand if there are two sensors of such telling me the temp of the engine, and seperatly telling the coolant temp.

Should be one sensor, which takes two readings at same time, one for you and one for ecu.
as I said, 001 engine showed 53c.
17 instrument cluster showed 65-75c. As coolest temp, don't remember exact fig

I will probably go with the sensor when the weather gets better. And also refill the system to check for the airlocks... + that's the cheapest option lol

if that doesn't work, I will give up and probably go to a decent local garage where I can be present during the work/diagnostics

Anyway, further ideas and device are very very welcome, this is proving very helpful... Keep them coming


I've added a little to it...
Hope it helps mate

With the thermostat guides (very rough)
You don't absolutely have to remove alternator, but it enables you to see what you're doing easier.
Sometimes it may also pay to remove top boost hose (completely)
 
Litcan91, did you ever resolve your coolant temp problem?
As I'm having exactly the same issue:

Temp gauge not rising above about 60 - 75deg, unless sat in traffic when it reaches the usual 90deg.
Changed coolant temp sensor with no change.
Oddly, the climate control diagnosis screen 51 shows engine coolant temp consistantly at 90 deg (after driving for approx 10mins) and remains there regardless of traffic etc.

How can I be getting 2 different readings from the same sensor, unless its the gauge or the new sensor that's faulty??

Or is it the thermostat? Any suggestions?
 
Litcan91, did you ever resolve your coolant temp problem?
As I'm having exactly the same issue:

Temp gauge not rising above about 60 - 75deg, unless sat in traffic when it reaches the usual 90deg.
Changed coolant temp sensor with no change.
Oddly, the climate control diagnosis screen 51 shows engine coolant temp consistantly at 90 deg (after driving for approx 10mins) and remains there regardless of traffic etc.

How can I be getting 2 different readings from the same sensor, unless its the gauge or the new sensor that's faulty??

Or is it the thermostat? Any suggestions?


Hi mate, I've changed sensor & it started doing this, then I had thermostat changed by seat, and it hasn't changed anything. I think the temp sensor that I've changed is dodgy (said original but from eBay & shiped from Poland) I've been busy, but my next course of action is to buy a coolant sensor from seat. And change it.

Where did you get your sensor from?
 

Ah ok, I think darksite are pretty reputable in vag stuff, but I've never tried them. Well as I've said before, I've only changed mine due to vcds showing it as a fault and the temp guage was sometimes randomnly droping from 90-0 and going back up instantly like it cut out.

After change it started doing the never get to 90 sceneapart from traffic. The sensor I naught was apparently original too & listed from the UK. But the packet was from Poland.

Il update as I change it to one from seat. But that will probably be in 2-3 weeks time
 
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I had the thermostat changed by a garage after giving up myself using 24" of extensions on the socket wrench. The angle was obstructed by the bulbous shape of the stat housing and the alternator. I think the mechanic moved the alternator to get it done. It is now reaching and reading 90 degrees again, woohoo. :D