Greenman986S
PCGB Member
ive said it before
Dieselgate...
Dieselgate...
Cayman 718 GPF Failure
- Thread starter Wrightrubber
- Start date
Hi Guys & Girls
Without prejudice
Following on from my last post, and our constant questioning regarding the lack of back pressure found when the oil ash % figure reaches 100%, and the subsequent warning light that comes on, that would fail the Mot test.
It just gets you thinking, there must be something very wrong with the algorithm that affects the sensor reading. We know from Porsche's Patent publication regarding the (Method for determining the loading state of a particulate filter), that this reading goes through a filtering process to provide syn-chronized integrals.
In layman's terms, this is what it means
Synchronized integrals" generally refers to specialized mathematical methods used in numerical analysis and control theory to achieve synchronization in complex or chaotic systems, or for solving certain types of integral equations. They are a theoretical concept with specific, high-level applications rather than an everyday engineering tool.
Well this could explain it all.
Facts are as follows.
1. No credible pressure readings from the differential pressure sensor at 100% full, or indeed on any other measured values we have seen.
2. No credible soot readings, because the sensor values are non existent, which would explain why we never see a soot warning light or message on the dashboard.
Yet we have instructions on what to do if it comes on in the Drivers Handbook?.
3. Its obvious the algorithm is controlling the soot and oil ash % figures, because the pressure sensor is clearly not.
4. The pressure sensor is not picking up the back pressure that should be there if the 100% oil ash is real.
5. It seems that when a regeneration is carried out, soot values can often be seen, why is this.
6. The Dealers are carrying out regenerations on our filters, when there is very little soot present, and there is no pressure in the exhaust.
7. The Dealers refusal to carry out a simple back pressure check on all our faulty cars, clearly confirms they know there is no back pressure in the GPF.
8. The existence of the internal memo sent to the Dealers in March this year, confirms they had this same issue, of not being able to re set the oil ash % figure then. And they even had the GPF modified to try and correct this fault.The modified filter was fitted to post December 2019 vehicles.
9. After the many cars that have had a new modified filter fitted, why are they in a position were they still cannot re set this oil ash % value, without having to do a regeneration on a new filter.
10. Why is the adaptation facility to reset the differential pressure sensor and the oil ash % values not on these cars
11. Why are they now telling us on the cars that have had modified filters fitted that an oil ash % reading over 50%, is acceptable and no further work will be carried out on these cars and the technical ticket requests will be cancelled.
12. And finally why are Dealers still trying to charge their own customers to fit a GPF filter that will not fix these cars.
I know I keep going on, but the more you look at the current situation we have on these Cars, the more Ridiculous it is.
All we need is Porsche to stop this silliness and look after their customers like they should do.
Dave
Without prejudice
Following on from my last post, and our constant questioning regarding the lack of back pressure found when the oil ash % figure reaches 100%, and the subsequent warning light that comes on, that would fail the Mot test.
It just gets you thinking, there must be something very wrong with the algorithm that affects the sensor reading. We know from Porsche's Patent publication regarding the (Method for determining the loading state of a particulate filter), that this reading goes through a filtering process to provide syn-chronized integrals.
In layman's terms, this is what it means
Synchronized integrals" generally refers to specialized mathematical methods used in numerical analysis and control theory to achieve synchronization in complex or chaotic systems, or for solving certain types of integral equations. They are a theoretical concept with specific, high-level applications rather than an everyday engineering tool.
Well this could explain it all.
Facts are as follows.
1. No credible pressure readings from the differential pressure sensor at 100% full, or indeed on any other measured values we have seen.
2. No credible soot readings, because the sensor values are non existent, which would explain why we never see a soot warning light or message on the dashboard.
Yet we have instructions on what to do if it comes on in the Drivers Handbook?.
3. Its obvious the algorithm is controlling the soot and oil ash % figures, because the pressure sensor is clearly not.
4. The pressure sensor is not picking up the back pressure that should be there if the 100% oil ash is real.
5. It seems that when a regeneration is carried out, soot values can often be seen, why is this.
6. The Dealers are carrying out regenerations on our filters, when there is very little soot present, and there is no pressure in the exhaust.
7. The Dealers refusal to carry out a simple back pressure check on all our faulty cars, clearly confirms they know there is no back pressure in the GPF.
8. The existence of the internal memo sent to the Dealers in March this year, confirms they had this same issue, of not being able to re set the oil ash % figure then. And they even had the GPF modified to try and correct this fault.The modified filter was fitted to post December 2019 vehicles.
9. After the many cars that have had a new modified filter fitted, why are they in a position were they still cannot re set this oil ash % value, without having to do a regeneration on a new filter.
10. Why is the adaptation facility to reset the differential pressure sensor and the oil ash % values not on these cars
11. Why are they now telling us on the cars that have had modified filters fitted that an oil ash % reading over 50%, is acceptable and no further work will be carried out on these cars and the technical ticket requests will be cancelled.
12. And finally why are Dealers still trying to charge their own customers to fit a GPF filter that will not fix these cars.
I know I keep going on, but the more you look at the current situation we have on these Cars, the more Ridiculous it is.
All we need is Porsche to stop this silliness and look after their customers like they should do.
Dave
Dave, I don't pretend to have the knowledge or expertise you have on this subject but it sounds like these vehicles are not operating as intended or perhaps even as certified and since the issues appear to be the software and hardware controlling the exhaust and by default the emissions from the car it is might be time to play hardball if you are confident of your diagnosis.
I understand the allure of involving the press directly but I would be more inclined to advise Porsche GB that since they have not been as supportive as we would expect on this issue the only course of action to resolve it would be to bring it to the attention of the relevant government body such as the
Driver & Vehicle Standards Agency and present them with all the evidence collected to date so that they can undertake an official investigation. Further pressure could then be applied by advising that the motoring press will be informed of of this action and kept informed of any progress.
After all the recent attention regarding cheat devices on VAG vehicles to distort actual emissions it might just be the leverage needed to get then to start listening and cooperating.
If any of this is teaching you to suck eggs then I apologise in advance of your response.
I understand the allure of involving the press directly but I would be more inclined to advise Porsche GB that since they have not been as supportive as we would expect on this issue the only course of action to resolve it would be to bring it to the attention of the relevant government body such as the
Driver & Vehicle Standards Agency and present them with all the evidence collected to date so that they can undertake an official investigation. Further pressure could then be applied by advising that the motoring press will be informed of of this action and kept informed of any progress.
After all the recent attention regarding cheat devices on VAG vehicles to distort actual emissions it might just be the leverage needed to get then to start listening and cooperating.
If any of this is teaching you to suck eggs then I apologise in advance of your response.
My speculation, but it does seem as if Porsche is pushing back a bit on this as it is getting difficult to obtain reports from OPC's, who appear to be digging in and saying that the way to get your CEL to go out is to replace the GPF. They don't seem to want to explore any other diagnosis. So, £9,000 please sir. If you don't want us to fix it, please take your car away.
If a customer does get a new GPF, then the light usually goes out. We don't know what else they may do at the same time but we do know that the process has been unsuccessful in two cases where a full strip down has not solved the issue. As Dave states, everything points to a software issue and an inability to re-set the values, hence the replacement of the GPF still involves one or more attempts at regeneration. Of the cars that have been fixed, most are quickly showing ash values of 50% or more, which Porsche now states is quite acceptable as long as the car is running fine, without a warning light on. This is the problem with going to the press at this point. Porsche says there is no issue other than the fix being a replacement service item at £9k. Despite all we have learned at this stage, we have little factual basis for countering that view. It is their stated opinion versus ours. Many owners of these cars will be driving around blissfully unaware that they have a potential problem. The normal MOT emissions test will not show up any faults (other than you won't get a pass with a CEL on).
As stated above, it does seem as if we are getting to crunch time on this matter. Some things need to happen which would give us more traction. It would help our cause if:
- a car that has had a new GPF has the CEL come back on
- the DVSA takes an interest on the basis of a potenntial emissions fault
- an OPC refuses to divulge the VAL report results or to do any investigation other than read the code off the PIWIS
- other models start to have similar issues
- we are able to identify a different fix by engaging and independent to follow this through.
We also have a case that the cost of repair is unreasonable. Who buys a car of this value where there is a service item costing £9k. We are into McLaren, Ferrari and Bugatti teritory. Posche reworded their extended warranty terms to specifically exclude the GP Filter This in itself suggests they don't think these are a few isolated instances.
We might also have an argument about not allowing fair competition. Porsche independent specialists can only try a forced regeneration to fix the problem, and it does not work medium term. They ultimately have to refer back to an OPC who will charge £9k. Porsche have been rightly criticised for not permitting others to repair PDK gearboxes, differentials or other major components and not selling spare parts. This would be the first time they have applied that approach to a service item.
We are some way towards getting what we need re the above matters. We need to be careful to obtain as much written support as possible. We are also trying to form a group of owners out of the open cases that Dave has got, to work together, compare notes and build a compelling argument about the unfair and unreasonable treatment they are receiving.
At this point, with all Dave has done over 2 1/2 years, we will have leverage and get some legal advice.
Any thoughts and contributions are welcomed!!
If a customer does get a new GPF, then the light usually goes out. We don't know what else they may do at the same time but we do know that the process has been unsuccessful in two cases where a full strip down has not solved the issue. As Dave states, everything points to a software issue and an inability to re-set the values, hence the replacement of the GPF still involves one or more attempts at regeneration. Of the cars that have been fixed, most are quickly showing ash values of 50% or more, which Porsche now states is quite acceptable as long as the car is running fine, without a warning light on. This is the problem with going to the press at this point. Porsche says there is no issue other than the fix being a replacement service item at £9k. Despite all we have learned at this stage, we have little factual basis for countering that view. It is their stated opinion versus ours. Many owners of these cars will be driving around blissfully unaware that they have a potential problem. The normal MOT emissions test will not show up any faults (other than you won't get a pass with a CEL on).
As stated above, it does seem as if we are getting to crunch time on this matter. Some things need to happen which would give us more traction. It would help our cause if:
- a car that has had a new GPF has the CEL come back on
- the DVSA takes an interest on the basis of a potenntial emissions fault
- an OPC refuses to divulge the VAL report results or to do any investigation other than read the code off the PIWIS
- other models start to have similar issues
- we are able to identify a different fix by engaging and independent to follow this through.
We also have a case that the cost of repair is unreasonable. Who buys a car of this value where there is a service item costing £9k. We are into McLaren, Ferrari and Bugatti teritory. Posche reworded their extended warranty terms to specifically exclude the GP Filter This in itself suggests they don't think these are a few isolated instances.
We might also have an argument about not allowing fair competition. Porsche independent specialists can only try a forced regeneration to fix the problem, and it does not work medium term. They ultimately have to refer back to an OPC who will charge £9k. Porsche have been rightly criticised for not permitting others to repair PDK gearboxes, differentials or other major components and not selling spare parts. This would be the first time they have applied that approach to a service item.
We are some way towards getting what we need re the above matters. We need to be careful to obtain as much written support as possible. We are also trying to form a group of owners out of the open cases that Dave has got, to work together, compare notes and build a compelling argument about the unfair and unreasonable treatment they are receiving.
At this point, with all Dave has done over 2 1/2 years, we will have leverage and get some legal advice.
Any thoughts and contributions are welcomed!!
Apologies if this has already been covered. The Google response to my question regarding finance company liability suggests that finance companies are equally liable along with the dealer…has anyone tried ?
On a different note this problem has certainly put me off upgrading my pre dpf 981. I have maintained the Porsche warranty throughout, but the thought of a £9k bill is enough to make me hang on to my current car. It’s very short sighted of Porsche. The actual cost of the dpf to Porsche must be far less…so they seem to be charging for the new DPF at full dealer margins for what is a contentious replacement.
On a different note this problem has certainly put me off upgrading my pre dpf 981. I have maintained the Porsche warranty throughout, but the thought of a £9k bill is enough to make me hang on to my current car. It’s very short sighted of Porsche. The actual cost of the dpf to Porsche must be far less…so they seem to be charging for the new DPF at full dealer margins for what is a contentious replacement.
Thanks John, I think that's a very clear summary and leads me to think that we're almost there.
The one thing I find strange is that the issue appears generally to be limited to one model and a distinct period unless I've misunderstood that. I can't imagine that the software or hardware for the Cayman would be significantly different to Boxster's of a similar age or configuration or even 911s based on the propensity of manufacturers sharing as much as possible across platforms to keeps costs down. If true that suggests there is something unique about the 2.0 Caymans of a certain age and perhaps a comparison with some Boxster models with similar spec, age, mileage etc. might be in order to see if there is a significant difference between the models although I understand this might be a bit subjective.
I also wonder if it would be possible to compare the engine management software between models, ages etc. to see if there are any obvious differences in the omissions code and associated algorithms that might account for this anomaly. Perhaps a friendly tuning company might be interested in helping with some analysis since Porsche themselves are clearly reluctant to cooperate with us to reach a conclusion.
I reiterate, I am far from qualified in grasping the technical side of this issue but like many have a desire to help if I can even if sometimes I might be stating the bleeding obvious through my lack of understanding.
The one thing I find strange is that the issue appears generally to be limited to one model and a distinct period unless I've misunderstood that. I can't imagine that the software or hardware for the Cayman would be significantly different to Boxster's of a similar age or configuration or even 911s based on the propensity of manufacturers sharing as much as possible across platforms to keeps costs down. If true that suggests there is something unique about the 2.0 Caymans of a certain age and perhaps a comparison with some Boxster models with similar spec, age, mileage etc. might be in order to see if there is a significant difference between the models although I understand this might be a bit subjective.
I also wonder if it would be possible to compare the engine management software between models, ages etc. to see if there are any obvious differences in the omissions code and associated algorithms that might account for this anomaly. Perhaps a friendly tuning company might be interested in helping with some analysis since Porsche themselves are clearly reluctant to cooperate with us to reach a conclusion.
I reiterate, I am far from qualified in grasping the technical side of this issue but like many have a desire to help if I can even if sometimes I might be stating the bleeding obvious through my lack of understanding.
Hi Voodoo_Blue
Without prejudice
Regarding other models, we have had issues with the 718 Boxster 2.0 and 2.5, and model years up to and including 2023.
We also had a similar issue with a December 2018 991 GTS recently.
We managed to convince the Porsche Dealer that quoted the owner to replace the Bank 1 GPF filter to cover the cost under warranty.
Again we used the data from the GPF report which showed several readings that didn't look right.
We had a 100% oil ash reading on bank 1, and 58 % on bank 2.
The Dealer authorised bank 1, but refused to do bank 2.
The reason why we asked them for help was the readings didn't look right.
1. The soot loading didn't look right, all the same, impossible
2. The exhaust temperatures again all the same, how could bank 1 temperatures be the same as 2 when the GPF is supposedly blocked.
But they are all CALCULATED afterall.
3. Our favourite sensor, a reading of -0.25 hPa, in my experience that could well be a faulty sensor.
Enclose the GPF report below for your attention.
In my opinion this GPF report looks like it maybe controlled by the same algorithm controlling our 718 cars, because again it makes no sense at all.
Any feedback on this post would be appreciated
Dave
Without prejudice
Regarding other models, we have had issues with the 718 Boxster 2.0 and 2.5, and model years up to and including 2023.
We also had a similar issue with a December 2018 991 GTS recently.
We managed to convince the Porsche Dealer that quoted the owner to replace the Bank 1 GPF filter to cover the cost under warranty.
Again we used the data from the GPF report which showed several readings that didn't look right.
We had a 100% oil ash reading on bank 1, and 58 % on bank 2.
The Dealer authorised bank 1, but refused to do bank 2.
The reason why we asked them for help was the readings didn't look right.
1. The soot loading didn't look right, all the same, impossible
2. The exhaust temperatures again all the same, how could bank 1 temperatures be the same as 2 when the GPF is supposedly blocked.
But they are all CALCULATED afterall.
3. Our favourite sensor, a reading of -0.25 hPa, in my experience that could well be a faulty sensor.
Enclose the GPF report below for your attention.
In my opinion this GPF report looks like it maybe controlled by the same algorithm controlling our 718 cars, because again it makes no sense at all.
Any feedback on this post would be appreciated
Dave
Attachments
Thanks for the clarification Dave.
Looking at the evidence to date it very much sounds like a software issue or the possibility that the software and hardware it is designed to manage and/or receive data from are misaligned. The only way to confirm this would be to analyse the code and understand what it is supposed to do in relation to the parameters that have been set and how that relates to the data being recorded and sent by the sensors that the programme uses to calculate the status of the filters etc. I wonder if anyone knows of someone that has the capability to access the ECU and scrutinise the relevant code related to this issue.
The other thought I had based on the above was that this issue sounds very reminiscent of the DPF problems on diesel vehicles where the filter gets blocked over time if the vehicle's exhaust never gets hot enough to regenerate the filter due to being subjected to lots of short journeys. Do we have any evidence that the cars you have been involved with have any similarities in how the cars have been used? If not could we do a quick survey to understand if there are any similarities in driving behaviours or usage patterns?
Let me know if I can be of any further assistance.
Looking at the evidence to date it very much sounds like a software issue or the possibility that the software and hardware it is designed to manage and/or receive data from are misaligned. The only way to confirm this would be to analyse the code and understand what it is supposed to do in relation to the parameters that have been set and how that relates to the data being recorded and sent by the sensors that the programme uses to calculate the status of the filters etc. I wonder if anyone knows of someone that has the capability to access the ECU and scrutinise the relevant code related to this issue.
The other thought I had based on the above was that this issue sounds very reminiscent of the DPF problems on diesel vehicles where the filter gets blocked over time if the vehicle's exhaust never gets hot enough to regenerate the filter due to being subjected to lots of short journeys. Do we have any evidence that the cars you have been involved with have any similarities in how the cars have been used? If not could we do a quick survey to understand if there are any similarities in driving behaviours or usage patterns?
Let me know if I can be of any further assistance.
Last edited:
Hi Voodoo_Blue
Without prejudice
Following on from my last post, I would like to share some more information regarding our Oil Ash loading issue.
Vehicle control systems monitor the minimum pressure drop achieved after a full regeneration event. This value is used in algorithms (soot models) to determine the ash volume and adjust soot accumulation estimates and regeneration frequency, preventing premature or excessive regeneration due to ash-induced backpressure. A higher post-regeneration pressure drop indicates a higher ash load.
So if our filters had physical ash present in a percentage form, you would expect to see more soot regeneration requests on your dashboard. Instructing you to carry out road testing with lots of deacceleration involved as instructed in your drivers manual.
This is because the GPF filter would be getting full of ash, and the room for soot would be reducing so more soot regenerations would be needed.
So why are we not getting these soot regeneration messages, which leave a DTC code, before the Ash % gets to 100%
We have never, ever had a soot regeneration message on any of the faulty cars we have dealt with, which is unbelievable, when supposedly the GPF is blocked with ASH, and the GPF needs replacing.
Again the differential pressure sensor doesn't know the difference between soot or ash, it just works on pressure and this information is fed into the algorithm, and the algorithm does the rest.
So the only way to affect this Ash %, (thats never present in these filters), is to carry out a regeneration, which is designed for soot control only, yet according to our cars data no soot is present and no pressure is seen.
This Patents method for determining the loading state of a particulate filter of a motor vehicle is well documented, but it doesn't cover the maintenance or any means to adapt any of the measured or calculated data shown on our GPF reports.
And the fact that on our cars the adaptation facility to reset the differential pressure sensor and GPF doesn't seem to be available, makes this situation worse.
We will be checking other vehicles that are displaying abnormal oil ash % readings to see if they have the adaptation capability going forward.
Had a call from an owner two weeks ago that had his car into a Dealer recently with a supposedly blocked filter, the Dealer quoted £9k to replace the filter.
We asked for a back pressure check to be carried out, and what would it cost, and he was told £1,500.00 to remove the exhaust and carry out checks, but it could be more.
This is going to stop, and these Dealers who are blatantly exploiting this situation will not be forgotten, we have a detailed database covering all the people caught up in this situation, and its still growing after 2.5 years.
Sorry to repeat myself, but if anybody comes on to our forum looking for answers, if they have this issue, they will read 2.5 years worth of research covered in several recent posts.
Dave
Without prejudice
Following on from my last post, I would like to share some more information regarding our Oil Ash loading issue.
Vehicle control systems monitor the minimum pressure drop achieved after a full regeneration event. This value is used in algorithms (soot models) to determine the ash volume and adjust soot accumulation estimates and regeneration frequency, preventing premature or excessive regeneration due to ash-induced backpressure. A higher post-regeneration pressure drop indicates a higher ash load.
So if our filters had physical ash present in a percentage form, you would expect to see more soot regeneration requests on your dashboard. Instructing you to carry out road testing with lots of deacceleration involved as instructed in your drivers manual.
This is because the GPF filter would be getting full of ash, and the room for soot would be reducing so more soot regenerations would be needed.
So why are we not getting these soot regeneration messages, which leave a DTC code, before the Ash % gets to 100%
We have never, ever had a soot regeneration message on any of the faulty cars we have dealt with, which is unbelievable, when supposedly the GPF is blocked with ASH, and the GPF needs replacing.
Again the differential pressure sensor doesn't know the difference between soot or ash, it just works on pressure and this information is fed into the algorithm, and the algorithm does the rest.
So the only way to affect this Ash %, (thats never present in these filters), is to carry out a regeneration, which is designed for soot control only, yet according to our cars data no soot is present and no pressure is seen.
This Patents method for determining the loading state of a particulate filter of a motor vehicle is well documented, but it doesn't cover the maintenance or any means to adapt any of the measured or calculated data shown on our GPF reports.
And the fact that on our cars the adaptation facility to reset the differential pressure sensor and GPF doesn't seem to be available, makes this situation worse.
We will be checking other vehicles that are displaying abnormal oil ash % readings to see if they have the adaptation capability going forward.
Had a call from an owner two weeks ago that had his car into a Dealer recently with a supposedly blocked filter, the Dealer quoted £9k to replace the filter.
We asked for a back pressure check to be carried out, and what would it cost, and he was told £1,500.00 to remove the exhaust and carry out checks, but it could be more.
This is going to stop, and these Dealers who are blatantly exploiting this situation will not be forgotten, we have a detailed database covering all the people caught up in this situation, and its still growing after 2.5 years.
Sorry to repeat myself, but if anybody comes on to our forum looking for answers, if they have this issue, they will read 2.5 years worth of research covered in several recent posts.
Dave
Again Dave, I'm far from capable in understanding the technical side of this so let me see if I've got it correctly.
Ash is formed as a result of the engine burning oil and soot is formed as a result of the normal combustion process.
The particulate filter is designed to reduce the volume of soot or ash entering the atmosphere.
The way the car monitors the current load in the filter is by measuring the back pressure on the filter and presumably it should get higher as the filter loads up with ash or soot.
In theory the volume of ash produced should be fairly low unless the engine burns a lot of oil or oil deposits escape the engine via the exhaust system.
The filter is designed to be regenerated (regen) by following the relevant instructions in the user manual and in doing so burns off the soot deposits at high temperature thereby reducing the back pressure and freeing up space in the filter to catch further soot (and ash) deposits.
Since the sensor measuring the back pressure can't distinguish between ash and soot it would be reasonable to assume that there will be more soot than ash once the threshold has been reached for the sensor to trigger a warning message to prompt the driver to carry out a regen.
This does not appear to be happening in relation to the cars where this fault has occurred, it simply defaults to "Consult a Dealer" and their default is replace the filter at circa £9k.
The filter is designed to last for a significant period i.e. more than 100k miles through normal use.
The filter is not deemed to be a normal service item as it is not mentioned as such in the service schedule.
If all the above is correct then I have some questions (not necessarily for you Dave).
What is actually causing the back pressure sensor to trigger the warning message?
Is the sensor working correctly?
If the sensor can't distinguish between soot and ash the software must assume the default is soot especially in the earlier years of the cars life so why is the regen message not being triggered as stated in the manual?
Is there any way to check if this assumption has been included in the code?
If the default message is to "Consult a Dealer" then is the back pressure at such a high level the algorithm thinks the filter is blocked?
If so why was a regen message not generated before the filter attained a critical load?
Does the code include different thresholds to generate different messages?
Are these thresholds staged and the outcome of regens measured to see if a lower threshold has been reached confirming the successful reduction of soot which resets the system or not if the reduction of soot fails to reach the lower threshold which may then trigger a further message to "Consult a Dealer".
If the filter is blocked with ash then why is the car burning so much oil or allowing oil to escape via the exhaust?
If the filter isn't blocked with ash why was the regen message not triggered once the threshold was reached for that process to be implemented?
Has anyone checked the back pressure sensors to see if they are working correctly?
Has anyone asked for an old filter back after replacement for independent analysis to check the extent of ash or soot buildup?
Do any other manufacturers suffer the same issues with their filters or is this issue unique to Porsche?
I'm not sure if any of the above is of any help so forgive me if I'm talking nonsense.
Ash is formed as a result of the engine burning oil and soot is formed as a result of the normal combustion process.
The particulate filter is designed to reduce the volume of soot or ash entering the atmosphere.
The way the car monitors the current load in the filter is by measuring the back pressure on the filter and presumably it should get higher as the filter loads up with ash or soot.
In theory the volume of ash produced should be fairly low unless the engine burns a lot of oil or oil deposits escape the engine via the exhaust system.
The filter is designed to be regenerated (regen) by following the relevant instructions in the user manual and in doing so burns off the soot deposits at high temperature thereby reducing the back pressure and freeing up space in the filter to catch further soot (and ash) deposits.
Since the sensor measuring the back pressure can't distinguish between ash and soot it would be reasonable to assume that there will be more soot than ash once the threshold has been reached for the sensor to trigger a warning message to prompt the driver to carry out a regen.
This does not appear to be happening in relation to the cars where this fault has occurred, it simply defaults to "Consult a Dealer" and their default is replace the filter at circa £9k.
The filter is designed to last for a significant period i.e. more than 100k miles through normal use.
The filter is not deemed to be a normal service item as it is not mentioned as such in the service schedule.
If all the above is correct then I have some questions (not necessarily for you Dave).
What is actually causing the back pressure sensor to trigger the warning message?
Is the sensor working correctly?
If the sensor can't distinguish between soot and ash the software must assume the default is soot especially in the earlier years of the cars life so why is the regen message not being triggered as stated in the manual?
Is there any way to check if this assumption has been included in the code?
If the default message is to "Consult a Dealer" then is the back pressure at such a high level the algorithm thinks the filter is blocked?
If so why was a regen message not generated before the filter attained a critical load?
Does the code include different thresholds to generate different messages?
Are these thresholds staged and the outcome of regens measured to see if a lower threshold has been reached confirming the successful reduction of soot which resets the system or not if the reduction of soot fails to reach the lower threshold which may then trigger a further message to "Consult a Dealer".
If the filter is blocked with ash then why is the car burning so much oil or allowing oil to escape via the exhaust?
If the filter isn't blocked with ash why was the regen message not triggered once the threshold was reached for that process to be implemented?
Has anyone checked the back pressure sensors to see if they are working correctly?
Has anyone asked for an old filter back after replacement for independent analysis to check the extent of ash or soot buildup?
Do any other manufacturers suffer the same issues with their filters or is this issue unique to Porsche?
I'm not sure if any of the above is of any help so forgive me if I'm talking nonsense.
Posts made and opinions expressed are those of the individual forum members
Use of the Forum is subject to the Terms and Conditions
