So bought a new to me 2014 Octavia diesel. Had it 4 days and driving along the dual carriageway at 70 and the dash suddenly lit up and warned me the engine temperature was high. Indeed the needle was in the red. So slowed down, set the heating to high and engine temperature dropped back down within 60 seconds. After that it was fine, even after dropping the heating back down. Managed to recreate it twice since in a similar scenario (70mph) with the same result, pop heating up and it’s sorted.

Anyway taken it to the garage I bought it from and they’re having a look. I’m guessing the thermostat is at fault but does anyone know if the car will store the maximum coolant/engine temperature? Feel like a bit of a fraud as it only seems to work under specific scenarios.

Odd thing is it didn’t? happen in a 30 mile motorway journey when I picked the car up nor travelling 50 miles to goto the zoo. Odd.

It might have been doing a regen at the time? The fact that putting the heating on reduced the temperature means it hadn’t dumped its coolant.

I had a Golf diesel that did this and it was a blown headgasket. Other symptoms were red hot air coming form the air vents, and coolant bubbling out of the expansion tank followed by low coolant warning. So it prob isn’t headgasket if none of those other things happen 🙂

VAG cars seem to cry wolf rather than actually be attacked by wolves, so it may be a sensor issue. Or the thermostat.

could just be the coolant has been refilled (as part of a service or whatever) and not bled properly. If so, your actions (whilst wise) won’t have actually fixed anything, the problem normally goes away as most systems are self-bleeding, but you need to keep a VERY careful eye on levels over the next few days

Thanks for the responses. Coolant level is fine with no obvious leaks and no emulsification of the oil. Could be a temperature sensor, we’ll see.

My folks’ 15 plate Fabia had a problem with the water pump jamming that gave them an intermittent overheating problem. Might be worth looking into (theirs got replaced under warranty, apparently it was relatively common)

Similar thing happened to me late last year with my 14 plate Octavia – as above was a water pump sticking and was fixed under warranty. Garage where I had it serviced were scratching their heads but the main dealer knew the issue right away.

Been fine since.

So garage have replaced the thermostat and feel that’s fixed the issue. We’ll see if I break down on the M1!