Hi,

Ive had my octavia CR LE now for a couple of months and noticed something odd the other morning.

When stopping and switching the car off after an hours driving at 70mph, the fan ran on for about 10mins afterwards. I thought this was strange as the outside temperature was only 4 degress and has never happened before.

Is this normal?

Thanks

Nathan

Hi,

Ive had my octavia CR LE now for a couple of months and noticed something odd the other morning.

When stopping and switching the car off after an hours driving at 70mph, the fan ran on for about 10mins afterwards. I thought this was strange as the outside temperature was only 4 degress and has never happened before.

Is this normal?

Thanks

Nathan

Others will be more knowledgable, but mine does this too at times. I had a turbo Saab that had similar behavior so I didn't really think about it.

It will be the DPF doing a regen!

Yep, DPF will have been doing its thing.

thats good to know as i have had the same thing happening and did think its strange as its been so cold recently.

Thanks for the replies guys.

It only ran on for about 5 mins after stopping.

Does it normally tell you that it is doing a regen, as nothing came up on the dash?

Cheers

Nathan

Does it normally tell you that it is doing a regen, as nothing came up on the dash?

No, others have noticed a drop in the MPG read out and a burning smell outside the car.

Other than that no visual signs.

As luck would have it I just arrived home and had the same thing, burning smell and fans running.

Is it bad to stop or will it have done it's thing by that time?

I was tempted to go out for a drive but didn't. This is the second time mine has done this in 500 miles now.

This is normal behavior for all cars. Nothing to do with DPF. Just temperature of the coolant inside radiator to high due to stopping of natural airflow. If you do not want to hear how your fan working, just reduce your speed at last mile. This will be also good for your turbo.

This is normal behavior for all cars. Nothing to do with DPF.

Not true.

Perhaps in summer or in a hotter climate but in the UK at this time of year in these temperatures unless you are driving like a man poccessed it is far more likely to be your DPF.

Plenty of threads have already discussed this. A quick search will bring you up to speed.

As luck would have it I just arrived home and had the same thing, burning smell and fans running.

Is it bad to stop or will it have done it's thing by that time?

I was tempted to go out for a drive but didn't. This is the second time mine has done this in 500 miles now.

When the DPF is performing a regeneration it increases its temperature to burn off the sooty deposits it has collected.

This extra heat is what can contribute to the burning smell some people mention.

If the engine is turned off mid way through or immediately after a regen then this excess heat needs to be reduced as there is now no air flow through the engine bay, over the DPF or along the exhaust. The fan continues to run to aid cooling and reduce risk if you happen to be parked over long dry grass!

In order to increase the temperature more fuel is burnt which is why some people notice a drop in their immediate MPG.

If you turn the engine off mid way through a regen the system resets and you will then have to wait until your driving style meets the minimum requirements for another attempt at regeneration.

No harm will be done by switching off mid way through providing your DPF does eventually get a chance to regen before it fills/clogs to a point whereby a dealer visit is required, but don't worry you get a warning light well before. This is when you need to take the car for a longer steady run to allow the DPF to do its thing!

When the DPF is performing a regeneration it increases its temperature to burn off the sooty deposits it has collected.

This extra heat is what can contribute to the burning smell some people mention.

If the engine is turned off mid way through or immediately after a regen then this excess heat needs to be reduced as there is now no air flow through the engine bay, over the DPF or along the exhaust. The fan continues to run to aid cooling and reduce risk if you happen to be parked over long dry grass!

In order to increase the temperature more fuel is burnt which is why some people notice a drop in their immediate MPG.

If you turn the engine off mid way through a regen the system resets and you will then have to wait until your driving style meets the minimum requirements for another attempt at regeneration.

No harm will be done by switching off mid way through providing your DPF does eventually get a chance to regen before it fills/clogs to a point whereby a dealer visit is required, but don't worry you get a warning light well before. This is when you need to take the car for a longer steady run to allow the DPF to do its thing!

Thanks for the info silver1011.

I guess there's no way of knowing if the regen had finished at that point? Do you know roughly how long a regen takes or is that dependant on the level of soot present in the filter?

Thanks for the info silver1011.

I guess there's no way of knowing if the regen had finished at that point? Do you know roughly how long a regen takes or is that dependant on the level of soot present in the filter?

I'm not sure to be honest.

This is my gut feeling and not based on any hard evidence but I reckon if your DPF had started to regen then a portion of the built-up soot will have been burnt off, just not all of it.

So I reckon there is a good chance it might be some time before your car attempts to regen again...

Usually when a regen is happening and you stop at lights or a junction you will notice the revs dont drop below 1000, and then when the regen is finished it will be back around the normal 750 odd rpm, thats how i know anyway

oh and it takes about 20 mins to complete, but it is in the manual somewhere

Edited 23 January, 201115 yr by Dallan

I get that whith a 20 tsi le so its not a dpf check its just cooling the car down.

I get that whith a 20 tsi le so its not a dpf check its just cooling the car down.

Petrols run hotter than diesels.

If on a modern diesel the fans are running after the engine is turned off in January with the current ambient temperatures and you haven't just thrashed it home then it's far more likely to be due to the DPF.

Have a 1.8 turbo petrol FL......

had the same "problem".........................dealer advised me to let the engine run for a minute before and after a long journey............ allows the radiator to cool down the engine and the turbo........

>>>>>I think that lower temperatures outside would not affect the actual engine temperatures when running.....an engine would operate at a certain temp no matter what the outside temperature....

(just a thought... as i read posts where people said this thingy happened even when the outside temps were quite low..)

Have a 1.8 turbo petrol FL......

had the same "problem".........................dealer advised me to let the engine run for a minute before and after a long journey............ allows the radiator to cool down the engine and the turbo........

>>>>>I think that lower temperatures outside would not affect the actual engine temperatures when running.....an engine would operate at a certain temp no matter what the outside temperature....

(just a thought... as i read posts where people said this thingy happened even when the outside temps were quite low..)

Well when it was -15C before xmas i watched my temperature gauge plummet as soon as i pulled off the motorway so external temperature does have a big influence on engine temps. In this cold weather i struggle to get the oil up to 90C on a 20mile motorway journey. As soon as the temp hits 12C or above then it warms up in no time.

Well when it was -15C before xmas i watched my temperature gauge plummet as soon as i pulled off the motorway so external temperature does have a big influence on engine temps. In this cold weather i struggle to get the oil up to 90C on a 20mile motorway journey. As soon as the temp hits 12C or above then it warms up in no time.

as i said before

was just a thought !!!