unstable water temperature gauge

[Maff1976]

Hi, can anyone offer any advice on what would cause the temp gauge to randomly drop from 90oC down to nothing in a few seconds then rise back to 90oC during steady driving? The engine warms up fine and can sit at steady temp all day then drop back and forward on other journeys!

Cheers.

 

[Maff1976]

Hi, can anyone offer any advice on what would cause the temp gauge to randomly drop from 90oC down to nothing in a few seconds then rise back to 90oC during steady driving? The engine warms up fine and can sit at steady temp all day then drop back and forward on other journeys!

Cheers.

 

[olliep]

sensor or sender fail. common issue dude. have a look on the seatcupra.net 'infobase' theres something in there about using the aircon display as a diagnostics. number 51 is the digital readout from your coolant temp and this should help you to diagnose

 

[jamandspoon81]

hi,i have the same problem at the mo,its just a faults temp sensor,ive had it a few times,you can buy them off ebay for about £30 for a genuine vw part or £10 for a pat part,hope this helps

 

[J0N]

As above. I'd get it sorted though as this could have a detrimental effect on your cooling fans cutting in.

 

[lukecupra2001]

i been using the climate control coolant display alot lately cos the the needle lies!could say 90 on the dash but be way cooler on the display in climate control
http://seatcupra.net/index.php?option=com_content&task=view&id=341&Itemid=6

theres the link

 

[traumapat]

ive heard the dash gauge will read a steady 90 as long as the real temp is within safety margins. only once its passed this will the gauge actually move off 90. however thats for a working gauge.

if the gauge hangs back or moves between 70-90 for no reason as said it tends to be sensor/sender issue... either green top sensor in the coolant pipe or guage sensor that sits in the thermostat housing

 

[LEE69]

either green top sensor in the coolant pipe or guage sensor that sits in the thermostat housing

The thermostat as no sender, the dash dials and the ECU get the signal from the green top sender in the coolant pipe.

 

[Cupra Ross]

Very common problem, you need a new green top coolant temperature sensor. Any VAG dealer will know what you're talking about.

The VW Part Number is: 059919501A. Dual temperature sender 4 pin green 20MM

GSF Car Parts Part Number: 93494D TEMP SENSOR-4 PIN GREEN G4/BORA/ £16.50

 

[traumapat]

The thermostat as no sender, the dash dials and the ECU get the signal from the green top sender in the coolant pipe.

thermostat housing not thermostat itself.. theres another sensor that runs the gauge other than the green top apparently. ( green top hasnt fixed my gauge wander )

 

[LEE69]

There is no other sender my money is on your thermostat goosed, like mine was.

 

[LEE69]

Use the climate control info above, see what the temp is when the gauge tells you it is 90.
Or log it in vag-com.

 

[traumapat]

There is no other sender my money is on your thermostat goosed, like mine was.

Hmm just been looking and i cant see anything on another sensor. think its an older golf thing.
I`ll double check it against vagcom, but i reckon your right on the thermostat being goosed.(in my case)

 

[LEE69]

They are a snip to do tbh

http://www.seatcupra.net/forums/showthread.php?t=210977&highlight=thermostat

 

[Cupra Ross]

thermostat housing not thermostat itself.. theres another sensor that runs the gauge other than the green top apparently. ( green top hasnt fixed my gauge wander )

Replacing the green top coolant temp sender has fixed the wandering temp gauge and related loss of fuel economy on 2 of my previous VW group cars.

 

[traumapat]

Replacing the green top coolant temp sender has fixed the wandering temp gauge and related loss of fuel economy on 2 of my previous VW group cars.

Yep no argument that the green top can mess up the gauge... but not in this case, its already been changed .

 

[traumapat]

They are a snip to do tbh

http://www.seatcupra.net/forums/showthread.php?t=210977&highlight=thermostat

Nice diagram Lee. was looking at a TT thread on changing it. seems the only careful bit is not breaking the dipstick holder

 

[cypher007]

hmm

im about to do a coolant change on my TDi Toledo and have two questions:

1) is it worth changing the sensor at the same time even if it isnt playing up?

2) how do i check the temperature on my climate control readout? i thought it only had the internal car temperature setpoint etc.

3) is G12plus still the best VAG coolant to use or have they improved it yet again?

 

[LEE69]

Nice diagram Lee. was looking at a TT thread on changing it. seems the only careful bit is not breaking the dipstick holder

Borrowed diagram
Holder un-clips and can be moved to one side.

 

[LEE69]

im about to do a coolant change on my TDi Toledo and have two questions:

1) is it worth changing the sensor at the same time even if it isnt playing up?

2) how do i check the temperature on my climate control readout? i thought it only had the internal car temperature setpoint etc.

Follow the instructions from above, easy to read the climate control.
If 51 doesn't read 9o change the thermostat at the same time.