Temp Gauge not working

Cupra TDI 150

Active Member
Sep 25, 2007
287
0
Help !!!! My temp gauge isn't working on my 53 Cupra TDI, I used the search function and all I could find was about the thermostat.

I'm not 100% it is the temostat, as on the right hand side of the engine is a wire going to what must be a sensor, its located under the air intake pipe from the air box. When I wiggle the wire and plu seems to work for a split second ie moves up to 90 degrees then back 0.

Thanks

Duncan
 

Seatmann

Rough around the edges
Sep 16, 2010
5,568
9
Scotlanda
Coolant temp sensor, 4 wires? It does the ecu and the gauge and if it goes the temp gauge doesn't work. Mine used to do the same, give it a wiggle and it went up so I thought it might be the wiring but no, a new sensor cured it.
 

Cupra TDI 150

Active Member
Sep 25, 2007
287
0
Yeah sounds right, it first started going up and down but now it just doesn't work unless you wiggle the plug. I've tried to take the plug off but i can't seem to gwt it free. How difficult is the sensor to change?
 

Muttley

Catch that diesel!
Mar 17, 2006
4,987
31
North Kent
Not difficult, but you will lose some coolant. As far as the electrical connector is concerned:

I have had some difficulty undoing other connectors under the bonnet, and found that there is a locking catch that must be disengaged by pulling the tab backwards, in the direction of pulling the connector apart.

I've used the connector onto the brake fluid level sensor in the following photo's, because it's easy to get to.

The plug looks like this, end-on, when it's apart.
Conn-end-on.jpg


The socket is shown here, with the locking tab
Lockingtab.jpg


Here is a top view of the connector plug showing where the bit you pull on is located.
Connectassy.jpg


This is how it comes apart.
Pulltheclip.jpg


Hope this helps
 

seatturbopower

Active Member
Aug 1, 2012
350
5
birmingham
Help !!!! My temp gauge isn't working on my 53 Cupra TDI, I used the search function and all I could find was about the thermostat.

I'm not 100% it is the temostat, as on the right hand side of the engine is a wire going to what must be a sensor, its located under the air intake pipe from the air box. When I wiggle the wire and plu seems to work for a split second ie moves up to 90 degrees then back 0.

Thanks

Duncan

new coolant temp sensor mate.change that for the green type one and a good priced one also.mine was 25 euro alot i know but a o.e one so all good.some have said that cheap ones are just as good but from i brought the car the guy said he changed it few weeks ago............i buy the car on the same day light comes on EML light.
 

randomage

Active Member
Feb 23, 2012
49
0
South Devon
Just google them mate, they're that common to go that they're easy to find! I've had my 2nd go now, serves me right from buying a cheap one off ebay... Doesn't affect the car apart from the guage so far as I can tell, so I haven't bothered replacing it again. That and the fact it's held in with a makeshift clip, held on with about 4 plastic cable ties after the standard clip disappeared, allowing my engine to forcibly eject the sensor and most of my coolant - RAC men can be pretty imaginative!
 

Muttley

Catch that diesel!
Mar 17, 2006
4,987
31
North Kent
randomage, the temperature sensor unit contains two separate sensors, one of which feeds the dash gauge and another which is connected to the ECU. If the dash gauge is inaccurate you need, at the very least, to have the fault codes scanned; but the trouble is if the sensor is merely reading wrong but not completely failed the ECU will call for the wrong fuel quantity from the injectors.
 

randomage

Active Member
Feb 23, 2012
49
0
South Devon
Huh, that would spell issues.. Well the gauge is completely non-functioning, which was solved last time by the new sensor, but I think it has just died completely, engine behaviour hasn't changed and I haven't seen any drop in power or MPG yet. I'll probably get round to replacing it next time I have a garage to play in, just annoying trying to do it outside in the cold, even warm coolant doesn't stop tender fingertips!
 

Cupra TDI 150

Active Member
Sep 25, 2007
287
0
All sorted now guys !!! Thank you all for your input. it was the coolant temp sensor. When changing the sensor be prepared to loose a fair bit of coolant so have plenty of rags about. I found removing the flexy pipe from the air box to gain better access

Again thanks for all your help!!
 

Seatmann

Rough around the edges
Sep 16, 2010
5,568
9
Scotlanda
I leave the plug connected, swap the sensor over then the plug, it can make it a quicker job. Still an awkward sod on the tdi though lol
 

greck999

SLOW work in progress....
Jul 10, 2009
396
1
Rugeley, Staffs
I changed my cts last night as my sensor was playing up and put my engine management light on. Temp always read ok on the dash.
I changed it for a genuine vag part, a green sensor.
Now the gauge hardly moves when I'm on the move. There is hot air from the vents and when I'm stationary the gauge will move to about a quarter.
Would these probs occur if there was an air leak and the water wasnt able to touch the sensor as I lost a bit when the sensor went in. Not a great deal as the engine was cold.
Hope somebody can help.
It's an 04 LCR. Thanks.

Neil.

Sent from my HTC Desire S using Tapatalk 2
 
Last edited:

greck999

SLOW work in progress....
Jul 10, 2009
396
1
Rugeley, Staffs
I have scanned and there is nothing. I imagine it could be the thermostat but its strange how it has started to do this since I changed my temp sensor...
:mad:

Sent from my HTC Desire S using Tapatalk 2
 

Cupra TDI 150

Active Member
Sep 25, 2007
287
0
Oh dear, possibly faulty sensor? I only managed to work out what to try by searching the froum I wasn't really sure what if changing the sensor would work. I also lost a fair amount of coolant, well more than I imagined i would loose. It almost emptied the expansion tank. Sorry i can;t be more help.
 

DrewCole

Spannering the Cupra
Oct 19, 2015
697
1
Braintree, Essex
I did this very job last night, my gauge used to rise and fall, with the EML on.

Since changing this my gauge doesn't move at all, I used the Green sensor too.

I did loose some coolant so wonder if the level dropped too much and there is now air in the system, I'll try to bleed it and see what that does....

Another job ticked off then added back to the list!
 

dgjdrummer

Part-timer
Nov 5, 2011
1,310
4
Wrexham, N. Wales
The system is self bleeding, run it for about 10 mins with the coolant cap off and you can just give some of the larger pipes a squeeze if you're in doubt but they generally don't suffer from airlock or anything.

Sent from potato.
 

DrewCole

Spannering the Cupra
Oct 19, 2015
697
1
Braintree, Essex
I played around with the plug on the sensor and the gauge on the dash started working when stationary, but dropped when driving.

So think that would point to the thermostat needing to be replaced.


Sent from my iPhone using Tapatalk