Temperature not reaching 90 - again?

Mewcenary

Full Member
Mar 16, 2006
156
0
Farnham, Surrey
Hi,

This happened before and was rectified with a new thermostat, but about a month after the same thing is happening: Temperature gauge never quite gets to 90, will fall back to 0, then up again, then down...

Seems a bit strange for the thermostat to fail twice in quick succession. Is there anything else I should be looking at?
 

mattfas

Active Member
Apr 6, 2009
97
0
leeds
could be your temp sender if its the original black one thats in you can bet its that thats faulty if it is the black one id change it for the green capped one anyway
 

meltonlad

Active Member
Mar 21, 2009
391
0
huntingdon
i think i would change the temp sensor. you can get them on ebay for about £10 and only takes 2 mins to change. the sensor is on the right handside of the engine. black or green colour cap held in by a small plastic clip.
 

Mewcenary

Full Member
Mar 16, 2006
156
0
Farnham, Surrey
Mine seems more likely to drop at low speeds. On the motorway it will just about make it to about 80-85 (then maybe drop again) so some level of temperature is being sensed, just not quite right!
 

Mewcenary

Full Member
Mar 16, 2006
156
0
Farnham, Surrey
i think i would change the temp sensor. you can get them on ebay for about £10 and only takes 2 mins to change. the sensor is on the right handside of the engine. black or green colour cap held in by a small plastic clip.
Can't spot anything green. Got a photo or link to a guide? Grrr, wish there was a Haynes manual for this car.
 

meltonlad

Active Member
Mar 21, 2009
391
0
huntingdon
its on the side of the engine. i think if you follow the rad top pipe it goes to where the sensor is. it will have a 4 wire connection pluged into the top of it.
 

Dyscontinued

Active Member
Apr 15, 2007
1,142
4
Leeds
Mine's done this for about a year, just never got around to changing the temp sensor.

If you have a look around there's plenty of info and a photo on what to do. My problem is they're all on the Cupra R not the diesel so don't really help me.
 

mikeholroyd

Guest
Have noticed this on both the Leon and the Octavia. Heater output seems OK though, even when temp sitting at 75. Perhaps it's just a VAG thing?

It's certainly not enough of an issue for me to worry that something's wrong.

Mike
 
Aug 7, 2009
1,395
0
Manchester U.K
If temp sensor is replaced and it still wont get to temp then it sounds like thermostat, if you changed the stat and its still doing it it sounds like the temp sender.
 

mikeholroyd

Guest
I should have mentioned that if the outside temperature is over about 4 or 5 degrees, the temperature on both cars goes straight up to 90 within a few minutes. The temperature on both the Leon and the Octavia only sit at 75 if the outside temperature is closer to or below freezing.

Spoke to a neighbour yesterday about this as well -- he has an Ibiza TDI on a 55 plate, and his does exactly the same too.

Mike
 

danny m

Active Member
Apr 16, 2009
321
0
hi

if you change your black top temp sensor to a green one is its a straight swap, do you have to do anything through vag com to reset it? just want to double check. :):)

cheers
 
Aug 7, 2009
1,395
0
Manchester U.K
IF you dont have acsess to vagcom no, it will clear its self, if it has no major symtoms like missfire, it will simply re-learn its self after a drive cylce :) . If you have symtoms like missfire etc revving from cold start then its best to clear all faultcodes etc.

If its first started then it will take a while to get to temp in this weather, but after driving should sit nicely at 90. If its going up on idle and dropping when you drive then thats most likely the thermostat as it isnt controling the temp of the engine. If the temp gauge is just giving an inacurate reading, or wont stay steady then its likely to be the sensor as these are the only 2 that can cause these problems.
 

OFI

Active Member
Sep 5, 2007
350
0
Salisbury
Can't spot anything green. Got a photo or link to a guide? Grrr, wish there was a Haynes manual for this car.

Take both engine covers off and you'll see it on the right hand slide close to the engine near some pipes. Can barely see the green (especially if you have a black one!) but it has one cable with a connector plugged in the top.

Replaced mine The other day and saw 90 degrees for the first time in a few weeks :D
 

ts743

Guest
Reviving a few old threads here having just acquired a 2001 Cupra 1.8 20VT - All was fine while I test drove it, but on the journey home the engine management light came on. Have yet to scan for codes, but have noticed my temp gauge is doing exactly this - Taking a long time to warm up and will maybe pop to 90, but mainly sits at 75 and occasionally dips lower. Driving at speed, or in traffic seems to have no effect. My question is, if it is the thermostat that has failed, am I going to be doing any damage driving it like this? Does anybody know what sort of money I should expect to pay a garage to replace?
 
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Will89lcr

Active Member
Jun 6, 2013
183
0
I had this issue so changes the sensor and had no luck, gna change the thermostat next
 
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