More bad news sadly, but hopefully some light at the end of the tunnel.

After monitoring soot levels, demanded regens and exhaust temps over my recent journeys, mostly longer runs at speed, the soot levels will rise from 5-6g to over 20g in only 20 or so miles of driving. Even at speed on longer runs. Some (surprising) observations:
- The vehicle is not demanding regens. Even with well over 17.6g of soot, a full tank, engine temps high and cruising at 60+mph. This is not good and there’s obviously something inhibiting demanded regens.
- I can get my IID-indicated soot levels to over 27g without the amber warning coming in. This is bizarre. When this happens I generally bottle it and manually demand a regen using my IID before I get a red and go into RP whilst driving.

On the bright side, the vehicle is going in with a DPF specialist next week. Whilst not LR indie, I had a very good chat with them on the phone to discuss how they do their diagnosis. They said all the right things about treating the cause and not the symptoms and to give them credit, they seemed to really know their stuff. We spoke about intake side leaks, blockages and pressure differentials over the DPF and how the problem was almost never the DPF itself. I’m willing to give it a go and see where we get to.

Anyway, this is where I need your help again to make sure I’m armed with the right info once they have diagnosed so I can ask the right questions and have confidence they’ve done a decent job of it:
- High pressure smoke test - what’s the boost pressure of the intake system under load, i.e. what pressure should we be hitting to make sure the test is valid?
- DPF differential pressure - What pressure values should I be expecting with a clear DPF?
- DPF soot content - What pressure should I be seeing that would indicate the DPF is full/blocked?

If I know these figures I can ask questions like: what pressure did you see when you tested the DPF? Etc…

Thanks as ever in advance! 🙏 Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!

More than any pressure values tell the garage that the ECU has an unrealistic regen count logged. Can you again confirm the count for demanded regens, completed regens and failed regens in your GAP IID tool?
The garage will likley put their own pressure gauges on the DPF and rev / load the engine to see any restriction based on experience rather than any JLR specific parameters. 2012 TDV8 Vogue (L322)

Ajmngn - What’s the actual model number on the newly fitted pressure sensor? I can 100% confirm that anything other the the exact revision that came out will artificially read higher levels as the voltages are not the same it MUST be the “AA” revision and not the identical looking “AB” version.

JayGee - the number of demanded regens is currently 105 and the number of successful regens is 45. There is no field for failed regens that I can see unless called something else? Incomplete regen status is 1, partial successful regens is 0 and regeneration inhibited status is also 0. Obviously these numbers are well down on what I would expect to see for a 103k mile car. It’s almost certainly been reset in order to allow a garage to force a regen and that will be fine as long as they did actually empty the filter of soot when doing so. I’d put money in them doing this but not cleaning the pressure pipes when they did the main part of the filter!

If you’re interested, I’m ever more convinced there’s a partial blockage in the pipes between the DPF and sensor and that the voltage reading on the differential sensor is correct (as it’s brand new). Having done a lot of research on this scenario, if the car thinks the DPF is full (which is one of the scenarios of high pressure read by the sensor due to partially blocked sensor pipes) then the soot value increases at a rapid rate. The car thinks the soot level is much higher than is being displayed (because of the high pressure) so rapidly increases soot value to what it thinks it ‘should’ be . It would also explain why the voltage is at normal parameters at idle or very low revs and only starts increasing above the expected parameters when there’s higher loads on the engine. If either the high or low pressure pipes going to the sensor (see photo, yellow and blue highlights) are partially blocked then this will give the exact scenario that I’m suffering. I’m praying that this is the case as should be an easy fix if so!

Sorry yes there is no field for failed regens. I'm on a 145k and have 287 successful regens ( doesn't change) and 1123 demanded regens (goes up every time it regens at the 17.9g limit) Resetting the DPF counter is when it's replaced or physically cleaned off the car as it resets the ash accumulation ( i.e the total soot capacity of the PDF)so if a garage did it after a forced regeneration they shouldn't have. Can't see how a blocked sensor pipe would cause a higher pressure reading - it would either show low pressure if it was blocked upstream or the same pressure as upstream side of the DPF if blocked downstream. Hopefully when (previously thought the pic showed your exhaust) it's off the car the garage can solve the issue - good luck  2012 TDV8 Vogue (L322)

Last edited by JayGee on 26th Sep 2022 2:16pm. Edited 2 times in total

Just some other points based on my experience with the sensor.

With you theory around the blocked pipe you “should” of got a accompanying DTC of P2452 have you seen that? If you have did you check to ensure the rubber pipes are clear, not split and connected to the right pipe outlet on the sensor and the DPF (they are different widths internally)

Did you perform the learning routine when you installed the new sensor?

I eventually found my issue to be in the wiring harness, have you recorded the sensor voltage and given the connector to the sensor, the wiring to the engine bag and the wiring to the ECU plug a wiggle to see if there’s any spikes or drops as this will mess with the reading.

Any update on this Andy? 2012 TDV8 Vogue (L322)

I do and it's not good news I'm afraid...

Vehicle went into garage and on the test drive the exhaust was giving 4-500mbar of back pressure at only modest revs (2-3000rpm) so the DPF is properly blocked as we had feared. The two options are an off-car clean or a new dpf with quite a stark price difference between the options. Obviously, most people would go for a clean. However, what we do know about this car's history is that it has had a number of forced regens and dpf treatments by a garage that doesn't seem to know what they're doing. The killer evidence is the fact it's only on 105 demanded regens at 103k miles so, it's almost certain that a previous owner/garage has been unable to clear the red warning so reset the DPF to do this. The last invoiced forced regen/dpf clean (using cleaner pumped into DPF as only charged £25 + labour) was in 2019 and nearly 20K miles ago. Even 105 regens in that mileage seems iffy so I think that the previous owner went to someone else between 2019 and when they sold the car to the dealer in 2021. Obviously I can't prove this and it's just a hunch, but I reckon they got rid of it as they were sick of having DPF issues; they probably had yet another blocked DPF which was the final straw and then did a bodge on the cheap to make the problem go away before offloading the car.

Anyway, we are where we are and not where we want to be, so onward...

What's not mentioned much in this thread is how the extreme temperatures induced during forced regens can damage the integrity of the filter itself, sometimes even melting it into one lump. I've also been demanding numerous forced regens with my GAP tool just to drive it to try and troubleshoot, and to be able to get it to the garage without the DPF filling and getting the red warning. As such, I don't want to waste the £300-350 to have the dpf properly cleaned only for it to not solve the problem. So, I am going to have a replacement DPF put on so that I have a handle on exactly the status of my car as the previous owner has not been as sympathetic to it over 5 years in London as I plan to be during my ownership. The fact that I've already had a new EGR fitted under warranty only a few months back only adds further incentive to getting a replacement DPF as then the car will be much happier all around and I can monitor soot and regens from a known baseline going forward.

Obviously, people will want to know how much a new DPF is and it's not pretty...c.£2200+VAT and that doesn't include fitting. However, I'm currently investigating getting a refurbished genuine LR DPF from a company that specialises in doing this, and their products come fully flow tested and with a 12 month warranty. Their website says they have my DPF in stock but I need to speak with them on the phone to get prices tomorrow morn. I am hoping that it's significantly cheaper than a brand new part (which will also only have 12 months warranty) and we'll go from there.

Of course, I'm tempted to take a punt on getting my one cleaned and I would take that option first if the car hadn't had so many forced regens to date. Therefore, whilst more expensive, I would rather the certainty of a replacement DPF and if I can get a genuine refurbished one for a fair price then I think it's worth it to me.

As for intake-side, we don't think there are any issues there. However, with the car unable to breathe properly it's hard to tell until we can get a good flow out the exhaust and then we'll see how the car responds. More to follow next week once Ive had a replacement DPF fitted and got it back on the road.

My only parting comment is that the garage said that they have worked on over 1500 DPFs since they started doing this as a specialism. in that time they've only had to replace 6 DPFs and all of them were melted on the inside of the filter and all of them from excessive use of forced regens. Whilst I have nothing to back that up in terms of science, it seems a no brainer to me that the forced regen function on the GAP IID should be a tool of absolute last resort. And never, ever, reset your DPF unless it's been off the vehicle and flushed so you know all the algorithms are in balance! Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!

Sorry to hear that Andy but it was as I suspected and I have said in the past that forced regens should only be done if absolutely necessary. The DPF consists of a ceramic core to hold the soot and ash and infront of it a catalytic metal element which is use to raise the temps and it's likley this has melted so it's unlikely cleaning will fix it. I'd phone around some scrappers like Gentlemen of salvage and see if you can get a used one. Best of luck! 2012 TDV8 Vogue (L322)

guys I've not googled but have you seen any DPF innards melted?
My experience is that they are pretty robust. Mine was removed and cleaned so I would recommend that unless you know for sure it's melted. Cheers, Greg
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
2011 Vogue SE 4.4 with lots of toys in Stornaway

Should be easy enough for the garage to get an inspection camera in there to see. 2012 TDV8 Vogue (L322)

Any update on this Andy? 2012 TDV8 Vogue (L322)

Sorry for the tardy response. Not much of an update from my last post, however, in the interests of furthering everyone's knowledge:

- The DPF was taken off and sent to a cleaning specialist in Milton Keynes called DPF Clean Team. They do a 'no fix no fee' offer and their prices are very reasonable so it was worth the shot. Sadly, after 2 cleaning attempts they could not get the flow down to less than 40mbar and 10mbar is the maximum amount for them to declare 'clean' and support that with their guarantee. Therefore, the DPF monolith is damaged beyond repair.
- I and the DPF Clean Team have been searching high and low for a second hand DPF to refurb but have come up blank. I need the car back on the road and it had been a few weeks of trying, so I had to accept the inevitable and have brought a brand new DPF.
- I also had a very unfortunate incident whilst the car was in the garage in that my low pressure in-line fuel pump had seized and managed to partially melt the power supply plug. Not a difficult diagnosis or replacement, but it set us back by a few days sourcing the parts to be able to splice in a new plug.
- The vehicle is booked in to have the new DPF fitted next week on 29 Oct and once done we will need to ensure that the upstream aspects of the system are working correctly before declaring fine health and I can get the vehicle back.

The main question that both the garage and I have is what has caused the monolith to fail. We believe it has melted but the only way to prove this is to cut it open thus rendering it useless. However, our best guess is that it is the multiple forced regenerations that has caused it. I know the vehicle has had forced regens prior to my ownership (as detailed further up the thread). However, I've also had to force regens myself to keep the car drivable in an attempt to troubleshoot. We don't know what caused the DPF to become blocked so suddenly, triggering this whole sequence of events. However, once I got the initial red warning, I should have sought to have the DPF cleaned ASARP, rather than continuing forcing regens. Lesson learned!

Once the new DPF is on and the car has been given a clean bill of health, I shall be monitoring the soot levels much more regularly to ensure that the car is regenerating as it should and hopefully that will be the end of it!! Andy

2010 4.4TDV8 Vogue SE in Santorini Black with Ivory interior
2017 Audi SQ5 3.0 V6T Quattro in Volcano Red
2001 Audi Allroad 2.5 TDI manual with low-range in Highland Green. Currently SORN whilst undergoing some serious restoration!

Last edited by Ajmngn on 25th Oct 2022 7:53pm. Edited 2 times in total

The reason why forced regens should only be used in an emergency and why it was a return to dealer operation as it would always require additional investigations to identify the root cause of excessive soot and/or failure of the normal regeneration system. 2012 TDV8 Vogue (L322)

One stupid idea: what happend if turn around DPF? Other side is brand new.