Dreaded dpf warning light

Buxton2901

Registered User
Hi guys, got the dreaded dpf warning on the way home from work today .
Has anyone else experienced this? And can it simply be caused by the regen failing to complete on a few occasions?
Worried my dpf is blocked now and going to cause me issues
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rjwojcik

Registered User
Manual states DPF needs a regen. , drive in sport at least 60km/h for 15 minutes. Page 19.

I'd give it an Italian tune.
 

B5NUT

Well-Known Member
VCDS Map User
Unfortunately DPF's don't last forever, and a quick google search would give a life span of around 100K miles. Even running the car in a lower gear to get the engine hot won't help if the DPF has become very blocked. First thing is to read the codes, as it could be the sensor. If that's OK then it's an option of removing the DPF and having it professionally cleaned, next would be buy a new. With the final option is to have it gutted and then remap the car to remove the DPF sensor reading, however come MOT you could end up with a fail as it illegal to drive a car without a DPF, but strangely enough not illegal to remove them!!.
 

Bishop187

Registered User
Take it for a blast on the motorway, get the engine upto temp, then drive for bout 20mins with the revs between 2.5k-3k. See if that clears it. Good luck


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Buxton2901

Registered User
Thanks guys. Hopefully it's just due to failed regens as haven't been traveling far recently due to Boris and his clowns

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Buxton2901

Registered User
88k mate.
I had the dpf and egr blanked off on my A4 which fixed the issue but that car had 140k. Wasn't planning on having these issues so soon with my bitdi
Does Wynns dpf cleaner do anything or is that a gimmick?

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B5NUT

Well-Known Member
VCDS Map User
Cannot see that doing much good 325ml of snake oil to 40 litres of fuel, that's well watered down! Then it's going to be burnt in the combustion chamber then finally reaches the DPF... Only true way of cleaning out a DPF is removal and a chemical wash.

You don't usually get a warning message on the dash for a failed DPF regen, unless it's happened several times, but you know when a regen is taking place as the car smell's hot when you get out of the car and the front fans are going nuts. If that's been ignored then you need to take the car out for a good drive ideally on a motorway. If I find that is going on in my car I usually take it up the A1 for a couple of junctions and back home (approx 20 miles round trip) that has always done the trick and cleared any regen.

Get a code read on the car and see what the actual fault code is that's first thing I would do.
 

fatbadger

Registered User
On my previous car, with a VAG CR170 engine, I used to run the free Android app "VAG DPF" on my phone in a dash holder, connected to the car with a cheap bluetooth OBD dongle.
I found it really helped understand typical DPF behaviour - e.g. how quickly the DPF soot loading increased, and under what driving conditions, also how quickly (or not) it dropping during a regen and different driving conditions.

When I had it remapped, the soot loading increased noticeably quicker, resulting in more frequent active regens. Partly the reason I've been very reluctant to remap my BiTdi.
 

jetty

Registered User
I get this every so often. Even more so with the adblue system.
Just give it a blast down an A road in sport - the light will go off once regen has completed.

This fault pops up when a regen has been stopped part way through several times.
 

Buxton2901

Registered User
Download that vag dpf app and went for a drive. Before and after in attached. Soot level is down but shows oil ash residue is the same. bit sure what that means. Anyone?
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0d3256f759926eedad5c5c3a7d6211fc.jpg


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Bishop187

Registered User
Download that vag dpf app and went for a drive. Before and after in attached. Soot level is down but shows oil ash residue is the same. bit sure what that means. Anyone?
fade4285f7247e6a74b563eebb5627f1.jpg
0d3256f759926eedad5c5c3a7d6211fc.jpg


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Might have to check out this app. What obd dongle did u use? I got a feeling it won’t work with my obdeleven one


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Buxton2901

Registered User
I used the elm137 Bluetooth dongle that I use with carista mate. Was only like 5 or 8 quid from eBay or Amazon bought it years ago

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CupraDine

Registered User
Might have to check out this app. What obd dongle did u use? I got a feeling it won’t work with my obdeleven one

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It won't work with OBDeleven as they keep their adapter locked down, any cheap eml137 dongle that supports at least V1.5 should work. Mines a cheap ebay one.

Download that vag dpf app and went for a drive. Before and after in attached. Soot level is down but shows oil ash residue is the same. bit sure what that means. Anyone?

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Oil ash residue I beleive is the ash left behind from regeneration, this cannot be removed except by removing and cleaning or replacing the filter. Each regen can add to this and it takes away part of the filter that could be used for regen, meaning less soot can be trapped between regen cycles. Eventually it will become so full that it cannot trap enough soot and regen properly, this is when the DPF fails and needs replacing.
 

CupraDine

Registered User

rjwojcik

Registered User
Can you not just give it a proper hammering to blow the ash away?
 

fatbadger

Registered User
Download that vag dpf app and went for a drive. Before and after in attached. Soot level is down but shows oil ash residue is the same. bit sure what that means. Anyone?
fade4285f7247e6a74b563eebb5627f1.jpg
0d3256f759926eedad5c5c3a7d6211fc.jpg


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Looks reasonable I think.

Oil ash residue is the amount of ash that gradually builds up in the DPF over its life.
Each time a regen occurs and soot is burnt off, a tiny bit of ash remains, and it gradually builds up (if you're familiar with open fires or woodburning stoves, you'll know that every so often you have to empty the ash out as it'll never burn off....same principle here....except you can't empty it out!).

Anyhow the key thing you're interested in is Soot Mass - and this has two figures - "Calculated" and "Measured".

"Measured" is based on the pressure drop across the DPF as read by pressure sensors. This will rise, but can fall as well during regular driving (without an active regen occurring) if driving circumstances get the DPF hot enough for passive regeneration to occur. In my last car you'd start to see soot mass drop slowly once above EGTs of ~300ºC in some steady-state driving.
"Calculated" only ever seems to rise until an active regen is triggered, I think it's a failsafe way of ensuring an active regen occurs just in case the measured figures become inaccurate due to faulty sensors etc, so your DPF doesn't get blocked.

When either one of these gets above a certain limit - I think this limit varies between engines/cars but on my last car was typically in region of 16-20g - AND the car is driving at a steady enough speed (not just urban stop/starting), an active regen will be triggered. When this happens, additional fuel is post-injected to raise the temperature of the DPF to around 500-600ºC. If the driving conditions allow, this will cause the soot to burn off and you'll see the level gradually drop. Once the figures get low enough (and note they won't both go to zero, on my last car the "calculated" only ever got down to a few grams, whilst the measured went right down) the active regen will stop, temps will return to normal, and the "time/distance since last regen" counters will be zeroed.
If you stop the car before an active regen is completed, it won't necessarily re-start an active regen until it's all warmed up, driving conditions are right (steady speed etc) again. There's also a minimum amount of fuel needed in the tank for active regens to occur (not sure what the number is, but if you're running in the red, regens might be prevented).

Looks like you got 351 miles between regens which sounds like it's in the right ballpark.
My last car (a Yeti, with the VAG CR170 engine) would maybe do around 2-300 miles between regens when stock, when I switched over to the Stage 1 remap I'd be lucky to get half that as the rate of soot loading increased - which means it was regenning twice as often and therefore doubling the rate of ash accumulation (so potentially reducing the lifespan of the DPF). By 120k miles it was taking forever for each regen to complete, and was chucking out grey smoke during active regens, which I took to mean end of life of the DPF. Whether I was unlucky with a sooty map (it was from a very reputable tuning company) or whether this is an inevitable side-effect of tuning, I don't know - I doubt many people have really studied their rate of soot loadings closely enough to know? Hence my slight nervousness of remapping the Audi.
My stock BiTdi 320 seems to happily do over 500 miles between regens, I guess what's typical varies from one model of car/engine to the next, perhaps the DPF(s) on these are physically bigger and able to trap more soot ? I don't know.
 
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