Overheating Engine ?

[IanHamilton]

My Octavia II diesel is about five months old and lately when I turn the engine off, the electric fan keeps running for about five minutes. There is a hot smell from the engine but the temperature gauge is normal. This only happens once or so a week. Interestingly the last time it happened the weather was very cold and rainy. The car was driven within 15 minutes for another short trip and the problem did not occur. Any thoughts?

[Halcyon]

No first hand experience with this myself, but from a lot of reading, it sounds like a DPF regeneration. This is where the deisel particles in the filter are burned off. The build up is caused by too many short trips, without some longer ones that would allow the exhaust system to get to a temp. where this would happen as a matter of course.
I've had my deisel vRS for 7 months now and have not had this happen once yet, but nearly all my kms are done on longer trips.
As in most cases, the owners manual is your friend.

[Umai Naa!!]

It's normal for the fan to run on, to help stabilise temperatures.

It wont flatten the battery, because it wont do it if the voltage is too low.

Take it for a decent run at freeway speeds every few weeks, and see how it goes.

[DunlopRS]

so its not turbo cool down?

[IanHamilton]

It has happened on long runs (45 mins) on the freeway so I don't think it is a short trip problem. I have had cars in the past with electric fans but they never turned on except on really hot days. Does the DPF regeneration cause a hot smell? My last diesel (Jetta) never seemed to have this smell.

[K1W1]

The forced cooling on Skodas seems to be like many Skoda things, a little random. The fan came on on my car today when I got home and it was about 10C ambient at the time.
I would get it back to the dealer and at least get them to check for fault codes. If nothing else that means that there will be a record on file of a potential problem if anything happens in future.

[Mysticality]

Mine does it when the Oil Temp is 100^C+

If you turn off the car, and hear the fan still running, turn the ignition back on and cycle through the MFD until you see the "Oil Temp" readout. Check the temperature there, before you look further into the problem.

I know mine likes to run the fans from 100^C+, all the way down to about 90, which can take awhile.
This is oil temp, not coolant temp.

DPF Regen is done by running the engine lean and with more air, and only operates when the engine is running.
The best way to tell if a DPF regen is happening, is raised idle RPM, a more "truckish" sound from the engine and if you stand with your leg near(ish) the exhaust pipe, you will be able to feel the burning heat.
I know I can't feel anything when the engine is running normally.

[buzuki]

Actually a DPF regen injects more fuel, but not at once. It will fire several times after initial combustion to carry the flamefront into the opening exhaust valve to help heat the exhaust up for the regen process

[ox518]

It has happened on long runs (45 mins) on the freeway so I don't think it is a short trip problem. I have had cars in the past with electric fans but they never turned on except on really hot days. Does the DPF regeneration cause a hot smell? My last diesel (Jetta) never seemed to have this smell.

You are right. From my experience that the DPF regeneration only happens after a long run say 30+ mins on freeway because I think it only hanppens when oil temp reaches 90+c for a while. Mine does like that and it produces hot/burning smell.

[Helldad]

I've noticed mine do the 5-minute fan dance twice in 5 months. The last time was only yesterday after a drive home from the city, about 45 minutes in non-peak traffic. There are several warnings about being careful poking around the engine bay as the fan could start without warning even with no key inserted. Next time I'll check the oil temp as suggested by Mysticality.