We're going through a rather warm spell here right now and when I got home from work this evening I noticed my oil temperature up at 100 *C (the last few km of my commute is suburban driving at around 50-60 km/h). I also noticed that the fans weren't running, which I might have expected with the oil up at that sort of temperature.

I plugged in VCDS and checked some sensor values:

Coolant temperature was at 96 *C

Coolant temperature actual at the radiator outlet was at 88 *C

Coolant temperature specified at the radiator outlet was at 80 *C

Cooling Fan 1 duty cycle was at 10 %

Oil temperature at this point was down to 96 *C

I ran output tests on the fans: it cycled to 86 % duty cycle for a few seconds and I could hear them kick on, then off again when it dropped back to 10 %.

All fuses and relays are fine.

Given the difference between the setpoint and actual temperatures on the radiator outlet I would have expected the fans to be running.

Am I overthinking this or should I be worried?

Car is a 2012 Combi with CFGB engine and DSG. DSG thermostat just replaced.

I wouldn't worry about oil temperature per se.

What did the water gauge show?

If that's still at 90⁰ then you're OK.

If the fans run when tested that's fine

11 hours ago, mdauncey said:

I wouldn't worry about oil temperature per se.

What did the water gauge show?

If that's still at 90⁰ then you're OK.

If the fans run when tested that's fine

Temperature gauge is not a useful indication here: it will read 90 *C at any actual temperature between 75 and 105 *C - it's basically a fancy indicator light. Apparently VAG's logic is that people get nervous when they see the temperature needle moving around.

On 04/05/2025 at 18:54, chimaera said:

Temperature gauge is not a useful indication here: it will read 90 *C at any actual temperature between 75 and 105 *C - it's basically a fancy indicator light. Apparently VAG's logic is that people get nervous when they see the temperature needle moving around.

I've heard that too.

I can see their reasoning.

Hi, following this thread - my Octavia VRS Mk3 petrol had overheated once - now shows oil at 105C dropping to 98C when free wheeling. Suspect that the fan is not running as it should and cooling is by induced air flow only. BUT CANNOT FIND wher is the relay ? ?. I understnd it is actually a combined controller and relay in a plastic box - but where is it ?.

Any help with this problem will be VERY much appreciated.

Thanks

Yep agreed the dash temp only ever shows 90C - so no warning of impending overheat until coolant level is way down - by which time it is boiling.