Coolant temperature gauge fluctuations

[jakex181]

My temperature gauge seems to be fluctuating while im driving, it is slow to get up to 90 and seems to move from 90 back down 1 or 2 divisions and back up continuously. I have read many forums and believe it is an issue with the temperature sensor/main thermostat/inline thermostat.

I am just wondering if there is an order i should start replacing parts in or if i can narrow it down to one of these 3 possibilities.

I used to have VCDS but it no longer works so is there any ways i can tell physically rather than reading fault codes?

Also what are the part numbers for these components? I have a 56 plate golf GTi, im not sure if the BWA and AXX engines are different.

Cheers

Jake

[DomBacon]

I'm having the same problem at the moment as well

[GTi-Andy]

there seems to be a common theme running at the moment regarding these kind of problems
A lot of members seem to be having thermostat problems.

[lukemk5gti]

My temperature gauge seems to be fluctuating while im driving, it is slow to get up to 90 and seems to move from 90 back down 1 or 2 divisions and back up continuously. I have read many forums and believe it is an issue with the temperature sensor/main thermostat/inline thermostat.

I am just wondering if there is an order i should start replacing parts in or if i can narrow it down to one of these 3 possibilities.

I used to have VCDS but it no longer works so is there any ways i can tell physically rather than reading fault codes?

Also what are the part numbers for these components? I have a 56 plate golf GTi, im not sure if the BWA and AXX engines are different.

Cheers

Jake

Very common problem, do you have manual or dsg?

Manual has two, dsg has 3

Manual has main thermostat and inline thermostat

Main thermostat from VW is about £300, not sure about inline thermostat but it is cheaper.

Chances are both have gone or will go soon!

If you're a very capable mechanic, it can be done but it's a big task!

[GrayMK5GTI]

I had that exact problem: http://www.mk5golfgti.co.uk/forum/index.php/topic,80793.0.html

Fixed with a new thermostat

[jakex181]

i have a manual,

so am i right in saying it is not the temperature sensor and that i am best to change the main thermostat first?

Id do the job myself so as to reduce costs, does anyone know the part number required?

Jake

[lukemk5gti]

i have a manual,

so am i right in saying it is not the temperature sensor and that i am best to change the main thermostat first?

Id do the job myself so as to reduce costs, does anyone know the part number required?

Jake

I started with the main thermostat and although my gauge now reaches 90 it takes 30mins to get there which leads me to believe my inline is gone.

VW garage as I said is expensive but and independent then did it for €225.

I'm sure someone else can shed light on the part number but from what I hear, it's challenging enough!

[jakex181]

I have done some logging using Torque App on my phone, this is my first time using the app

Does this graph confirm that it is definitely the thermostat?

http://s18.postimg.org/on9dzg221/Screenshot_2015_01_14_08_02_38.png

[JMP]

I have done some logging using Torque App on my phone, this is my first time using the app

Does this graph confirm that it is definitely the thermostat?

It does look like your thermostat starts to pass coolant already at about 65 degrees. It should go to about 87, I think the main thermostat temp rating is that. I have same problem, mine seems to settle around 75 degrees when outside temp is about -15 degrees celcius. The analog needle shows 90 but the real temp is lower. When there was -23 degrees the analog meter didnt want to show 90 anymore.

I changed my inline thermostat on top of dsg box, but I still need to change the main thermostat also which requires more work.