Fans coming on even after short journeys

[Deleted member 77314]

I have an FR 184 ST Dsg. It's 5 years old.

Recently in the last two weeks I've noticed that the fans seem to be coming on once the ignition has been switched off even after short journeys. This happens nearly every time.

I'm aware the default response here is "DPF regen" but I don't think this is the case. I have an OBD2 app and dongle that tells me the DPF status and it seems ok.

I've just had the cam belt and water pump changed, but temps seem normal for both oil and coolent.

Any ideas as to what could be going on?

 

[Tonezz]

I only live about 3 miles away from work, sometimes after a quick blast home I can hear it blasting under the bonnet when I get out. Not even caning it either, must just be a MK3 Leon thing.

 

[black_sheep]

Workshop manuals are here:

General maintenance - Leon Mk3 Official Seat Workshop Manuals Link

Hi All! I obtained these a few months ago, and they've been a great use so far. Here's a link to all of the Seat Workshop manuals for the Leon Mk3 3dr/5dr. https://drive.google.com/drive/folders/1M4ofxxMgsFjE7hNWg6l4KuifelmdMUu0?usp=sharing...

www.seatcupra.net

Electrical wiring diagrams are near the bottom of the files in the drive, so feel free to conduct continuity checks.

There could be a number of reasons why the fans are running, ie short in the fan control module. However, fault codes would generally be picked up.

This self study programme explains how the coolant system works on a modern VAG engine:

http://www.volkspage.net/technik/ssp/ssp/SSP_222.pdf

It is also worth noting that just because OBD2 device tells you the DPF status is ok, it doesn’t mean that the system is not trying to regenerate - it attempts to regenerate to maintain an good status before partial or full blockage.

 

[BillyCool]

I'd suggest that you get VAG DPF and see what the state of your DPF is. You say your OBD2 App says it's ok? What app you using?

The only time when my 184 has done that is when it's unable to complete a DPF regen due to the short journeys not allowing it to do it's things.

Or you have a faulty temp sensor? That has been known to happen and doesn't always throw up a fault code unless you have VCDS.

 

[ChrisM75]

Its worth noting that a car is only 30% thermally effecient at best, so a 184bhp car is likely kicking out at least 300bhp in heat, which is about as much as 100 average domestic ovens. Modern cars are powerful and because of regulations have small, soft front ends, so the radiators are small, requiring the fans.

A few people have been concerned about my Cupra making a noise after switch off, had to explain its normal many times.