Hello. Recently the temperature gauge on my 2002 Octavia vRS is intermittent when the vehicle is starting a journey. The gauge will suddenly drop and then suddenly rise again, the rates of movement are the same as if the ignition is turned off (and back on). It seems to rise and fall as you go over bumps or stop and start. It is fine once the vehicle has propperly warmed up (say after 10-15mins), once warmed up, the gauge never moves from the normal running temperature. If you then park up for a while say an hour and then come back to car, it will be the same again, the gauge will be vague (risnig and falling) for the first 5 - 10 mins. I have looked for a loose connection under the bonnet, but it is bit like looking for a neddle in a haystack.

Any advice? Any comments? Could it be the temperature sender?

First of all try replacing the coolant temp sensor

These are VERY VERY common problem

Do a search on this and you will even find a step by step instruction on how to do it

The are cheap too £25.00 ish

Then check the guage , if you still have a problem it could be the dash pod

But check the sensor first

Sarah

sounds very much like the water pump on the 20vt ,but worth checking the cheaper end first.

worth checking any fault codes with VAG com if you can

It's not the water pump. That was replaced a couple weeks ago.

First of all try replacing the coolant temp sensor

These are VERY VERY common problem

Do a search on this and you will even find a step by step instruction on how to do it

The are cheap too

Just had a thought. This intermittent problem occured a week or so after the previous water pump fell apart (VW quality????). Could the problem be that a fragment of plastic from the old pump had become lodged near the temperature sensor and the movement of this plastic is leading to the intermittent temperature gauge?

PS. For the last 2 days the gauge has been normal.

Any thoughts?

I had exactly the same problem on my TDI, changed the sensor to a new 'green' one and averything is now back to normal.

I guess the 1.8T is similar to the TDI. :confused:

When you buy the new sensor, make sure you get a new 'O' ring and clip.

I see your point but the coolant temp sensor supplies the water temperature to the ECU, NOT that dashboard.

It is a dual temperature sensor which provides input to the engine ECU and the temperature gauge.

I see your point but the coolant temp sensor supplies the water temperature to the ECU, NOT that dashboard.

It supplies the info to the temp guage

:iagree: I reckon you'll find what happens is that the sensor sends a voltage to the ECU, which then uses it for engine management and also sends a signal to the gauge on the dash. None of the dials on a modern car are directly connected to what they measure like they used to be on older models: everything goes through the ECU. On my old Renault, all the needles used to jump to the left when you started the engine, in a kinda boot-up stylee...

My bad then, Im used to older cars which have 2!

I had exactly the same problem on my TDI, changed the sensor to a new 'green' one and averything is now back to normal.

I guess the 1.8T is similar to the TDI. :confused:

When you buy the new sensor, make sure you get a new 'O' ring and clip.

Hi lads, I have the same problem and I think it is really temp sensor, but could you tell me where is that sensor located under the bonnet?:confused:

Hi,

must be the time of year - mine's doing it too. Noticed it after changing water pump (52k mls, what a piece of c**p) and thermostat about two weeks ago, but pretty sure I didn't move anything near the sensor.

The sensor's in one of the hoses itself, held in by a clip type thing - dead easy to change but only do it with the engine completely cold.

Haven't actually got outside and changed mine due to snow, ice, etc but it's passenger side end of engine towards the front. On my vrs it's buried down under other stuff and quite hard to spot unless you know you're looking for it.

Bernie

I had this, changed the temp sensor and all is well again.

i also had this problem, the sensor can be changed in a few minutes by simply removing the engine covers x2, twist locks secure this in place they can be undone using a small coin if need be, location of the sensor should be easy once the covers are removed, face the engine bay look down to the right hand side of the engine there should be a pipe quite low down as thick as your thumb a horse shoe shaped clip holds it in situ, once removed the sensor should just pull out. ensure the engine is cold and water filler cap is off before trying to remove the sensor, you will struggle to un hook the wiring from the sensor but its not impossible be careful not to rip the wires from the conector block there is a little squeeze clip to undo it should come free with a little tooing and froing...ta da.... should be free now remove and replace sensor not forgetting to replace the "o" ring, plug it back in to the loom and off you go.... or as in my case you replace the afore mentioned sensor and get your light extinguished only for it to come back on within 500 miles hhhmm.. i hear you murmer.... so i decide it must be the thermostat (due to temp not getting to 90 and wavering between 70-80), which i am now psyching myself up to replace, wish me luck, the only thing to do after the thermo is something to do with an overadvanced timing issue and or the sensor that monitors the timng over advancement, does anyone know how to change the thermostat?.......and would the timing be advanced as a side effect of having a thermostat stuck open? (me thinks)........

Termostat is a inferno to change, took me many weeks just to find it. decided not to try yet, must remove whole generator first. got and octavia 1,8l 20v.