Ok, I've had my octi now for 5 years and nearly 100k miles, and the temperature gauge has always read 90 degrees (half way up the dial) when fully warmed up.

However, just recently, it has started playing silly buggers, and can read anything from cold to slightly over 90 degrees, even when I know it is warm. on my way home from work tonight, it was up at 90, then down at cold, and then finally settled about 80 degrees.

The fans are kicking in and out as they have always done, it isn't losing coolant, and there is no mayo in the oil.

A few years back, I did have the dirty temp probe in the header tank problem, resulting in the temp light coming on, but followed the instructions on here and not had that issue for a good 3 years now.

All the rest of the instruments are behaving, so any ideas what could be causing this?

Thanks.

Temperature probe in the header tank? I think that is just a level sensor, but will cause the light to come on if it reads low on coolant.

Coolant temperature sensors are common faults on these engines, I'd try replacing that first. If it's not that then it could be the thermostat.

As Tom says, the sensor in the header tank is just coolant level. I was thinking of the temperature sensor on the engine block too.

Pro tip for replacing that - buy and unpack the new one, and sort gaskets etc before removign the old one. You'll be able to replace it without losing more than a few tsp of coolant.

And PLEASE make sure you change it with the engine/coolant system COLD. I have seen it done hot and was not pretty :|

temp sender. easy fix

If you notice the coolant temperature drop (to 70-80deg) when coasting down long hills or when taking it easy at low revs, and the temperature creeping back to the normal 90 when idling, then it'll be the thermostat.

They have a habit of sticking open, or at least becoming very slow to shut.

Replacing it is fairly easy if you have the right tools. I'd recommend getting it changed before winter though.

Thanks guys, will have a look at changing these as soon as possible.

Cheers,

Andy

Mine did similar, a new 'stat sorted it.

Bit Fiddly to get to one of the nuts (13mm I think) on the housing but it's manageable with a socket set and a knuckle.

Does anyone know a place to get a good coolant temp sensor?

Any links?

Main dealer !!

Or Trade parts sepcialists (google is your friend)

Don't bother with copy parts, they tend to be crap

Is there anywhere to order genuine parts online?

Is there anywhere to order genuine parts online?

Techincally no, but a dealer somewhere may do mail order, I know TPS don't.

hey all,

I have recently replaced my coolant temp sensor on my octavia 1 vrs and reset the fault code however it keeps coming back.

Before I changed the sensor it was the engine warning light but the temp seemed fine, now I have changed it, it is the engine warning light and the temp only gets up to about 70-80. could it be the thermostat? what about the fault code that keeps coming back (still the coolant temp sensor code).

I replaced the coolant temp sensor with the green one everone said to use.

Help! (thanks).

Eric.

it is the engine warning light and the temp only gets up to about 70-80. could it be the thermostat?

Help! (thanks).

Eric.

Bar the light, that does sound like the stat is knackered

Bar the light, that does sound like the stat is knackered

Bar the light? I have double checked and it is still saying it is the coolant temperature sensor. could the one I installed have failed within a week? Am I completely stupid in thinking of disconnecting the battery for a few mins, then re-setting the faults and seeing if that works?

Or do you think it is because of the stat? I'm a bit confused why the engine fault is still up, surely the thermostat has its own fault code?

I dont think a thermostat issue will generate a fault code. Where did you source your coolant temp sensor?

I cant remember now but I think it was eurocarparts.

It was the green one too. do you think it is worth trying a new one again just in case it was a dodgy one? they dont cost much and are very easy to fit.

Concensus is the genuine sensors are the only ones worth buying. About £25. Do the same with thermostat.

Sounds to me more like a stat issue.

Edited 6 December, 201213 yr by Liverpool-Lad

I got a non-genuine one from ECP, been on 12 months or so and still going strong.

I got a non-genuine one from ECP, been on 12 months or so and still going strong.

Er, ECP normally supply OEM parts in the actual manufacturer's boxes, rather than ones with a VAG brand name on it.