I have a 2015 Superb 2.0TDi DSG and have had an issue for a while. After a journey, the cooling fans run after the engine is switched off. I know that it is normal for this to happen sometimes, but it has been getting steadily worse and now happens after every journey, even very short ones (2-3 miles) while the engine is not fully warmed up. The engine idles at 1000rpm and is acting like it is constantly trying to regen the DPF.

Also, possibly related is that during a long journey (2 hours +) I get "DPF fault". This ONLY happens on long journeys, which seems weird to me. This goes away when the engine is switched off and restarted.

It has been to an independant garage and they said the DPF is not blocked - "pressures OK"

The car was becoming reluctant to start, which I thought was the fans running the battery down, but I think was just the battery dying (it's 9 years old after all). I've now replaced the battery with a new Bosch unit, but the fan issue remains.

I do not do a lot of stop-start town driving. My journey to work is about 20 minutes of mostly country roads. It also gets pretty regular long runs.

Any ideas before I start throwing money at mechanics?

When it happens drive off again and do a couple of kms to allow the regeneration to complete.

 

The attempt at a regen from cold start (which aint never gonna happen!) is after several aborted regen attempts, when this was happening to me I was also doing 20km runs, they were not quite long enough from a cold start for the engine to get to regen temp and then complete the regen, another couple of km would have done the job which is what I did as described above.

 

Knowing that in the future (moving closer to town) my journeys would be shorter with maybe one 20km journey per week I fitted an EGR emulator/simulator, now the car regens once per 1000kms and I am unaware of it, in 4 years and 60K miles I have heard the fans running on after shutdown only twice.

@J.R. - no it happens even after a longish run.

It's not unusual for me to do 300-400 miles in a day. It probably does a run like this every couple of weeks.

Like I said, I only get the "DPF - consult manual" message on a run of 2 hours plus.

Whats your mean by egr simulator?

2 minutes ago, Orlinon said:

@J.R. - no it happens even after a longish run.

It's not unusual for me to do 300-400 miles in a day. It probably does a run like this every couple of weeks.

Like I said, I only get the "DPF - consult manual" message on a run of 2 hours plus.

 

Mine was regenning 3 times during a 1000km autoroute journey at wide open throttle towing a massive trailer massively overloaded then it was trying to regen every day after that, my journeys were either too short, 5km which we know isn't enough or 20km which was not quite long enough but should have been, it was all a result of the disastrous emissions fix rollback software which was done before I bought the vehicle.

 

I forgot to mention something important, after fitting the EGR emulator/simulator I paid to have the ECU reflashed with the original emissions cheat software, it was that which stopped the constant regenning.

8 minutes ago, Hunt332 said:

Whats your mean by egr simulator?

 

https://tafmet.pl/english/egr-valve-simulators/221-egr-valve-simulator-with-blanking-plate-for-vw-audi-skoda-seat-20-tdi-cr-ii-euro-5.html

@J.R. Just taken the car for a 40 mile (60km) run with a good chunk of motorway in the vain hope that the new battery might have fixed it.

Engine still idling at 1000rpm, start/stop disabled and fans running when engine off.

Do you have a Bluetooth OBD device to be able to read information from the ECU?

The VagDPF app is very useful for visualising the system (pressures, soot mass etc).

It would help understand if a sensor is not working properly & may help localise the problem.

 

It's not unusual for the fans to run when you stop the car but there is clearly a problem in your car if you have the DPF error.

My journeys are 65km twice a day. 

Despite mostly motorway mileage, my car likes to start a regen when I reach the sliproad at the end of my journey so often doesn't complete before I reach home ~4km later.

 

As a guess I would say the DeltaP sensor is blocked/not working correctly. 

This is the main reading used to determine if the DPF is empty or full.

If the garage said the DPF was not blocked, this would be what I looked at next.

 

@Gabbo - thanks for your reply. I did have an OBD device some years ago, but no idea where it is now.

Will any OBD2 read do? Even the cheap ELM327 ones from ebay?

I'll order one and give it a try.

23 minutes ago, Orlinon said:

@Gabbo 

Will any OBD2 read do? Even the cheap ELM327 ones from ebay?

I'll order one and give it a try.

 

I guess so. 

I have a dongle from Carista but didn't pay for the subscription. 

I can use the device with other free OBD apps and it shows in them as a ELM something...

 

I'll take a screenshot from home tonight to show you.

Like Gabbo says, you could do with an OBD reader and VagDpf (android only) to see what is happening.  There is some good info here on your journey times in the cold, the car needs a series of parameters to complete an active regeneration (post injection fuelling) which includes a minimum amount of fuel and no caution/EML lights and a few other things.  If the car has been slowly building up soot then it may have gone beyond its normal regeneration point and hence will require a much longer journey to complete a full regeneration.  The other thing that affects your regen rate is your ash buildup in the DPF, which is invariably related to how many miles the engine has done and is usually measure by differential pressure and converted into a measure.  On your longer journeys it is likely that the car is completing a passive regeneration, Im not sure why you would be getting a DPF fault though, but it is sometimes a sign that an EGR valve is on it's way out, how many miles has your car done?  

@globalste - I've ordered a cheapy OBDII bluetooth dongle.

The car gets pretty regular long journeys (200 - 300 miles, maybe twice a month). It has just over 130,000 miles. I ONLY get the DPF warning on a long journey, over about 2 hours.

Garage says diff pressure is OK, but they didn't tell me the actual numbers.

 

Interestingly, yesterday, I took someone to the railway station, about 10 miles away. We were running late so I was driving "briskly". The journey is mainly short sections of dual carriageway with lots of roundabouts (if you know Milton Keynes, you will know what I mean!) and took about 25 minutes. After this, I noticed that the stop-start began working normally and idle was back down to 800rpm. When I switched off the engine to quickly drop off a parcel, the fans didn't run. I wondered if the new battery cured the fault and the car just needed a bit of time to "learn".

I then drove home again (20 min) by the time I got there the idle was back up, the s/s disabled and the fans running. 😞 

 

Looks like I am going to York next week (400 mile round trip) - we'll see what happens.

Yes know Milton Keynes quite well.  
 

The life of a DPf can be around 150k miles, but, VAg DPF will give you the best idea what is going on.  Your 288 engine has two EGR valves and they’re less susceptible than the ea189 used to be but which is where a lot of the historical thinking can come from, it’s not infallible though.  Start/stop not working is a sure sign of either battery or an active regen running.
 

Did you have the battery fitted and coded or fit yourself?  They’re a glassmat battery and they don’t like just being swapped over

 

defo see how your long journey goes

@globalste 400 mile round trip: No change. Fans still running after engine off. "DPF. See user manual" error on dash after about 1.5 hours of driving.

 

I fitted the battery myself - Bosch EGM type. Is it possible coding the battery might cure this? Can I do the coding with my cheap bluetooth OBDII dongle?

 

Yesterday the car started behaving - s/s working, 800 rpm idle, no fans - I think because fuel was low. I guess low fuel stops the regens?

 

Will try the OBDII and VAGDPF app this weekend.

I don't think the battery or coding can cause this. 

I changed my battery 2 years ago & didn't change any coding and it's worked fine since. 

Assuming your battery was an AGM type before ?? 

 

I can confirm that VAG DPF works with a cheap ELM Bluetooth device. 

I've installed VAG DPF Lite and it works with my Carista ELM device...

 

I have been using Car Scanner which is a free app which can read DTCs, live data & is free...

 

Some fault codes or VAG DPF Data would give you an idea where you start looking..