Cayman 718 GPF Failure

[Cyclemotor1958]

Hi Tony, 911Hillclimber,

Yes your absolutely right, the article was well written and covered lots of facts about this issue, but unfortunatly its been forgotten about.

Hopefully the Porsche Post would like to do a follow-up account of where we are now, and what progress we have made, we will need a few more pages.

We hit 200 thousand views on this subject this morning, 2 thousand this week so far, which is brilliant, it just shows the interest out there regarding our push to get this fault sorted out.

Its unbelievable that in this current climate, the Dealers and Porsche are still wanting to fit this expensive GPF part, when they clearly know it doesn't fix this Ash % software calculation issue.

Dealers around the country have customers asking them why has the ash % returned on their new modified GPF filter's, and are still waiting for an answers.

We are concentrating on the UK market at the moment, its keeping us busy, but to us its an issue that can not go away, like the bore scoring problem. Because this fault is becoming a major miss diagnosis problem in its own right.

You only have to read the internal memo that covers this subject to understand why we are bringing it to the attention of people who are affected by it.

We shouldn't be worried about this light coming on when these cars are going in for an mot.

We shouldn't be in position where we are thinking about selling these cars because the cost of this repair, makes no sense at all, and its not needed.

We just need the Dealers to carry out a back pressure check on these cars when the code P242F presents itself.

Then is over to Porsche Technical to find a solution that fixes these cars properaly.

We are desperately trying to fix this issue ourselves, with help from our owners and drivers, we have got this far because of their help, and its always been appreciated, and will continue to be.

Enclose below is our club page showing are views.

We push on

Dave

 

[Cyclemotor1958]

Hi Guys & Girls

Following on from my last post concerning the functionality of the differential pressure sensors on our cars.

Its always been the case that when the fault code P242F appears on our dashboards, and are cars are plugged into a diagnostic tester we always find the following information.

No soot present, the measured ash is at 100% and the differential pressure sensor readings is usually less than 10 hPa.

And no reports that performance or fuel economy are present, in fact the cars are running fine, before the light comes on, and while its on.

We have said for years now that these filters are not blocked with Ash, and we have proved that there is no backpressure present when the light comes on and the car is being checked.

We have checked 3 cars for back pressure, and we didnt find any.

We have checked a Cayman this week, and carried out a differential pressure sensor check along with a back pressure check.

To do this, we connected a manometer into the GPF supply pipe to the sensor, then we connected the car to a diagnostic tester.

We got the engine warm and checked the differential pressure sensor readings on the manometer and the diagnostic testers read out.

You will see from the photograph that our manometer on the left hand side is reading 8.4 hPa and if you look at the testers screen you can clearly see the ash level K231 at 100%.

If you look below at the K251 current differential sensor measured value, you can see its 5.31 hPa, this is the differential pressure sensor reading.

So it's showing two differential pressure sensor measurements with the engine running at idle that do not support a blocked GPF filter.

These pressures converted to PSI are as follows

8.4 hPa = 0.1218316997 PSI
5.32 hPa = 0.0770150387 PSI

So a direct exhaust pressure taken, and a diagnostic testers reading, a conclusive test you will agree.

So yet again, we find no pressure, what we did find on this car was that the cars differential pressure sensor was the original one fitted at the factory and it was showing pressure even when the engine wasn't running, with the ignition on.

These sensors should self zero, and if they don't, it affects the pressure data going back to the algorithm.

When I contacted Stuttgart I wanted to ask them why a simple back pressure test, like the one we have done on this car, and the others wasn't included in the checks on the internal memo.

They passed me on to Porsche GB, they gave me a case number and asked me to contact them if I had anymore information.

Durring that time I tried to contact Porsche Technical several times, and unfortunately, I became a nuisance.

This resulted in me being told I had to stop trying to contact them, which I did.

I was only trying to ask this question

Why wasn't this back pressure check carried out as part of the diagnostic checks on these GPF filters, thats all.

Because if they did, they would find what we have found, no back pressure present.

And if they questioned the low pressure reading from the sensor, and did what we have done to this car, they wouldn't have recommended fitting a new modified GPF filter.

It seems inconceivable that they would ignore these basic diagnostic steps.

We will carry on with our back pressure checks and hopefully they will start to do them themselves and stop this miss diagnosis madness.

Dave

 

[Cyclemotor1958]

Sorry for the dark picture it was taken in the car last night very late in the evening.

I had to black out the cars details, and re photo the photo sent to me.

But you can just make out the shape of the manometer on the left showing the 8.4 reading along with the time 22: 49: 11, very late.

Dave

 

[patersont718t]

Morning Dave,

As you know, Porsche agreed to replace my GPF, but to the best of my knowledge, the differential pressure sensor wasn’t changed after the memo checks were completed.

After just 30 miles, the car was showing 3.14% oil/ash fill. I’ve since carried out a diagnostic check on the differential pressure sensor myself, and I’m getting the same results even with a brand-new GPF fitted. With the ignition on and the engine off, the differential pressure sensor is reading 2.65 hPa and never zeroes.

The car is going back to the OPC with my readouts, along with the information you previously shared regarding the sensor version you quoted.

I’ll also be requesting the diagnostic results for the sensor, including confirmation of exactly which sensor is fitted and, specifically, confirmation that it is not the original suspect sensor.

Thanks again for your help.
Tony

 

[Cyclemotor1958]

Morning Tony

Thanks for the information on the sensor, what you have found is typical of what we have been seeing for years.

For some reason these sensors are being ignored, and yet their function is critical to the information the algorithm needs.

Has you have found out, our cars do not have the adaptation function to reset the sensor or the GPF after replacement which is absolutely ridiculous.

It will be interesting to see what the Dealer thinks of your findings, you seem to know alot more than them about your car.

Again the memo tells them to check the sensor functionality, they obviously couldn't be bothered, But never mind they just fit a very expensive GPF on your car, that wasn't required, and Porsche paid for the their miss diagnosis.

Like all the other ones.

Dave

 

[Cyclemotor1958]

Hi Tony

A bit more differential pressure sensor information to back up our investigations regarding the checking of this very important sensor.

When these sensors fault, they stop showing a zero reading, when the ignition is on, engine off.

All these photos were taken from the same car, this car came into the workshop with the warning light on with DTC code P242F oil ash load measured at 100% K231.

We are looking at the differential pressure current value sensor reading K251.

The first photo shows a reading taken with ignition on, engine off. 13.43 hPa (this should be zero)

The second photo shows the idle reading of 22.22 hPa, ( this is far to high)

The third photo shows the reading of the new sensor fitted with ignition on 0.50 hPa.

The fourth photo shows the new sensor reading at idle 9.29 hPa

And the fifth photo shows the sensor reading after a regeneration was carried out to clear the fault code P242F, 0.33 hPa.

You will see the ash measured reading K231 is now at 0.00%.

The sixth photo shows two sensors, the old sensor is top sensor you can see the age of this sensor VW AG 38/18 TN3, 38th week in 2018, the original sensor fitted at the factory.

It will be interesting to see how old you sensor is

Dave

 

[Cyclemotor1958]

Morning all,

Look what our friends from the 718 Forum sent us yesterday, just shows the interest on this fault on our cars is attracting.

Some more positive news we got this morning, our 718 Boxster that had the adaptation done on the ash load last week as done over 500 miles with a zero ash reading.

At the same time we replaced the faulty differential pressure sensor, which was the original sensor.

After this sensor was replaced all the readings came back in line, and hopefully will continue.

We will keep you informed on the progress of this car as we go along.

Bearing in mind our cars do not have the adaptation of the GPF ash load in PWIS at the moment.

Dave

 

[Cyclemotor1958]

Hi Guys & Girls

Continuing on with our differential pressure sensor theory that our sensors are sending inaccurate information to the algorithm that is creating this ash accumulation percentage thats not real.

Ive managed to find a,

Standard 0-100 hPa Differential Pressure
Transfer Chart.

It shows the Exhaust Pressure in hPA versus Electrical Signal Output in Voltage.

When we see the GPF data on a car that has the GPF P242F code present oil ash load measured at a very high level, 100%.

We never see a differential pressure sensor reading high enough to support the Ash % recorded.

This Chart shows you the sensor readings in hPa and voltages and the Filter Status Interpretation.

And what a pressure in hPa would be required to substantiate a blocked GPF filter.

We certainly have never seen a GPF filter with anything near 60 to 100hPa recorded.

This is what you would expect if the GPF filter was indeed blocked.

Also enclose a copy of a GPF report showing the oil ash load measured reading at 100%, and the differential pressure sensor reading at 4.81 hPa.

How can our Dealers and Porsche still insist that these GPF filters are blocked with ash and need replacing.

Dave

 

[JohnCRS]

Hi Dave. I want to follow up on the article that was published in Porsche Post so long ago. It is about time we got an update in print. I am inviting anyone on here to let me have a few lines on their experience of this issue (a story), or to make any points that we should highlight. I and Dave can then meet to incorporate that with Daves 3 1/2 year history working on this issue and prepare something for Porsche Post.

The last article was published in Porsche Post in the April 2025 edition, page 74. https://issuu.com/porscheclubgb/docs/porsche_post_digital_march_2025?fr=xKAE9_zU1NQ It ended with a number of questions to which Porsche have failed to respond. We can start with those and the answers that we have come up with.

 

[Cyclemotor1958]

Hi John,

That would be brilliant, we have so much more information now from when we started.

I was out with Mark last Friday at the Bluebell Inn Arkendale, catching up on whats currently happening in our GPF world. We had a brilliant lunch, and it was great to catch up with my friend again.

If you remember it was Mark who brought this fault to our attention, page 5 on the forum, we are now on page 57, with 203 thousand views.

So yes, let's get together, we have lots to report on, we will probably need the whole day.

Dave

 

[Cyclemotor1958]

Hi Guys & Girls

I spoke a while ago about our attempts to reset the ash load % value using other OBD2 scanner diagnostic tools.

We attempted on three of our faulty cars to reset the ash load % value from 100% to 0.00%, but unfortunately, after an average of around 500 miles, it came back and put the light back on.

Although it was a bit disappointing, it proves that this ash % load is not real, because real ash can not come and go, unless it's a software calculation issue.

We have now used another OBD2 scanner diagnostic tool to reset the ash load to zero, and it's still at 0.00% after doing well over 500 miles.

At the same time, the owner replaced a faulty differential pressure sensor and carried out a back pressure check. We even had one of our owners who has recently replaced his own sensor, contact this owner, and he gave him brilliant instructions on how to do it, and a big thank you to him.

The sensor readings are now ok, especially when the ignition is on, and the engine is not running, the sensor now shows a zero value.

The old sensor was the original sensor, VW prt no VW 04L 906 051F.

The owner of this 2019 Boxster 718 is going this week on a road trip around Europe, probably driving over 2.5 thousand miles.

The work that's been done on this car has given the owner confidence to under take this journey, he has seen for himself, that there is no backpressure present when the software says the ash load is at 100%.

He's taking his diagnostic tool with him and will take readings along the way.

This software ash load % correction using these testers, without doing a soot regeneration, demonstrates clearly that this ash 100% reading is incorrect and always has been.

The internal memo from Porsche says, in some cases the OPF can be recovered, therefore a OPF regeneration should be attempted if the ash load doesn't not reset when the OPF regeneration is attempted. Then the OPF should be replaced and the vehicle retested.

So they fit a new modified filter, and the ash comes back, sometimes at such a high percentage, it's unbelievable.

We can't thank this owner enough for helping us carry on with our research and testing to provide information that confirms that these modified GPF filters are being fitted, and it doesn't fix the software ash % fault P242F.

It clearly shows that the lack of the adaptation function in the Porsche PWIS diagnostic tester to reset the ash load %, just makes this fault on these cars even worse.

It should be really easy to reset this ash load % level once it's proven that no backpressure is present when carring out the diagnosis of this fault.

After all, the differential pressure sensors have always reported very low pressure readings on our faulty cars, which also confirms that no backpressure is present.

Yet this critical diagnostic information is being ignored by the Dealers and Porsche time and time again.

What we have found using another OBD2 diagnostic tool is brilliant, it means that a pending Mot test in the future will no longer be a problem, and certainly not be a reason to sell these brilliant cars, that are loved and cherished by their owners.

We will keep you updated on his road trip journey and his diagnostic checks along the way.

Dave

 

[911hillclimber]

Another PP article loaded with this info can only keep a chance of Porsche GB/Germany reacting alive.
I feel they really do not care.

Maybe they have tried to find a correction to this faulty system and there isn't one? Perhaps they should ask the VW engineers to fix it for them!

I do hope the PP article will highlight the fact they are not co-operating at all and tell 'us' to go away, stop contacting them etc. Not a good image.

A brand that has lost it's contact to the customer, fails technically in this case and has/is loosing market share along with VAG as a whole. Not a good image either.

Keep going Dave, I doubt you will ever stop the chase and the hits on this thread prove you have LOTS of support from PCGB members.

Graham

 

[Cyclemotor1958]

Thanks Graham,

Yes we will not stop, untill they admit they got the diagnosis of this fault wrong, right from the beginning during 2019.

Ive said this many times, the internal memo says it all, its a detailed admission that regarding the diagnosis of this fault they did not include a back pressure check in the technician checks section.

Why not

And they also admitted a modified OPF filter was fitted to these cars from December 2019 to fix this P242F ash load fault.

They have continued to blame their customers for using the wrong engine oil, a driving style that didn't suit these cars, and incomplete service history.

And yet when we have challenge them on the data thats associated with the GPF systems control readings, they eventually change their mind, from your paying, to we will pay.

All of these 2019 cars produced before December 2019, should have had the modified filter fitted if Porsche believed that this was a permanent fix.

They obviously knew it wasn't

This became a case by case issue, not an admission they got it wrong.

We push on

Dave

 

[Cyclemotor1958]

Hi Guys & Girls.

We are still struggling to get our Dealers to do a simple back pressure check on these filters they say are blocked with ash.

This simple back pressure tests does two things, it reports the actual back pressure from the exhaust, and it checks the differential pressure sensor reading on the car.

In an ideal world they should be the same, on this car they were not, and this chap has saved his customer the cost of a very expensive DPF on this car.

The Landrover specialist said it needed a new DPF, SOUNDS FAMILIAR.

Just shows the need for correct diagnosis.

Dave

 

[Cyclemotor1958]

Sorry me again,

Its funny every time I post on this subject, after the post is sent, I think of something else I should have included.

Not so long ago I was asked by the Porsche Club to stop trying to contact Porsche Technical regarding the internal memo they sent out last March to their Dealers.

The reason I wanted to speak to them was to ask whey they didn't include a backpressure check on these cars when this fault presented itself, and could it be introduced.

It just seemed ridiculous that these expensive GPF filters were being fitted for nothing, and Porsche could have saved alot of money along the way.

When our owners go into the Dealers with this know fault they would expect that the diagnosis of this fault would be technically first class, no stone left unturned.

Just a fault code showing P242F ash load high, is not enough to prove these GPF filters are actually blocked, its just the beginning of a diagnostic process.

The memo sent to them, gives a list of things to check that would normally support a filter blocked with ash, providing the car had covered alot of miles.

I read the other day that 150 to 250 thousand miles is not unreasonable for the life of a GPF filter.

Our cars are not high mileage cars even when some of them are over 7 years old.

So my point is how can a Porsche Main Dealer refuse to carry out this simple back pressure check, and what is their justification for not doing so.

We have heard many times that the Dealers have been told by Porsche not to carry out this check, when we have asked the question, even when our owners have offered to pay for the test.

Over last 3.5 years we have managed to get 18 of these GPF filters paid for by Porsche after we have challenged the GPF data from these cars.

We asked for this backpressure check to be done on all these cars, and it was refused, and the modified GPF filters were fitted.

Could a technical person from Porsche GB, come on to our forum and explain to us why this backpressure check was not included in their recent internal memo brought out to fix this P242F issue.

If it was a mistake it was not to put it in, then no problem, mistakes happen.

But surely we can't go on with this major miss-diagnosis of an emission control part, it doesn't make any sense at all.

Dave








 

 

[Wrightrubber]

Hi Dave

I think the answer as to why they won't do a back pressure check is they know what the result will be!!! That will then categorically confirm the filter is not blocked and confirm they have mis-diagnosed this fault from day one!!
The fact that you have helped 18 owners save over £170,000 in costs is amazing, well done Dave.
I wouldn't hold my breath for a Technical person from Porsche to come onto the forum and explain why the back pressure check was not included on the list of checks to be carried out, this is typical Porsche, arrogant and the bottom line is the customer isn't important enough!!
Keep up the good work Dave.
Regards
Mark

 

[Cyclemotor1958]

Thanks Mark,

Your probably right about Technical, if you remember when you asked them if you could go down to Reading to meet them and discuss your GPF failure. They refused with the excuse they are not customer facing.

And you were left with your Service Manager telling you, if it blocks up again you will be paying this time.

No wonder you sold the car, months of trying to convince them to pay for the GPF, and lack of confidence from Dealer and the manufacturer on the diagnosis of this fault.

Three and a half years on, and we are still trying to convince them to do the right thing.

If Porsche Technical were convinced that these modified filters would fix this issue, why couldn't they have spoken to you.

A thousand views have gone on today on posts talking about back pressure.

Kind regards
Dave

 

[patersont718t]

Update on my progress so far.

GPF replaced, 30miles in and reading 3.41% fill level, diff sensor still showing 2.42hPa with engine off.

I contacted the OPC to request another meeting to discuss the differential pressure sensor, as when I checked the readings myself, the sensor would not zero with the ignition on and the engine off.

The OPC asked me to put my concerns in an email. Following that, they came back and said they would replace the differential pressure sensor as a goodwill gesture, but they would not confirm whether the sensor had actually passed the checks outlined in the Porsche memo and.

I then received an email from a Service Manager refusing to meet with me, stating that he was too busy to go back through my concerns and there positions on this matter was clear, bearing in mind they haven’t changed the sensor at this point.

After a further four email exchanges, he has now agreed to give me 30 minutes on Tuesday to discuss my concerns.

Hopefully, this will give me the opportunity to finally get some clear answers regarding the differential pressure sensor, the memo checks and the ongoing GPF issue (not going to hold my breath on this bit though) my main reason for wanting a f2f is to agree a surveillance schedule to ensue the issue is finally fixed

thanks again Dave for all your support

 

[Cyclemotor1958]

Absolutely no problem Tony, we need to shout, and shout about this miss diagnosis disaster till somebody has the decency to own up to it.

This is just another example of another Dealer not following the memo information Porsche sent to them.

Now I am repeating myself again, the memo says.

Check the OPF differential pressure sensor for correct functionality

If they had checked the sensor, they would have found it faulty, and Tony would have not needed to mention it after the repair was completed.

If the Dealers after seeing the none existent pressure readings on these sensors found when this trouble code P242F presents itself with the accompanying 100% ash figure.

Then carried out a back pressure check, found no back pressure and reported it back to Porsche Technical the whole landscape of this fault would have changed a long, long time ago.

If they did report or question the sensor readings to Porsche Technical it certainly would have been recorded on the Technical ticket thats generated when the Dealers ask for quidence on this fault.

Afterall this is basic diagnosis on a suspected blocked exhaust.

Then we get on to the attitude of this Dealer who sold Tony his car, its not the first time we have had dealings with Dealers who all of a sudden get very unfriendly when our owners start asking questions about whats happening with this ash issue.

Our Dealers are not following the Porsche memo diagnostic instructions to the letter, and Porsche are certainly not making sure they do.

Its BLOODY RIDICULOUS AND NEEDS TO STOP, its doing so much damage to the Dealers, and the Brand, and this brilliant car.

Hope your Service Manager turns up for your meeting

Fingers crossed

Dave

 

[Motorhead]

Agreed Dave. What a pathetic response from Tony’s dealer’s Service Manager. Totally unacceptable behaviour to any customer!

Porsche stonewalling from the highest level down, digging-in their heels and dealing with any issues on a case-by-case basis if forced to do so rather than admitting any liability. It smacks of corporate layers being involved.

Tony.

Depending upon the outcome of your discussion with the Service Manager, I’d be inclined to get the Dealer Principal involved if you’re still not satisfied completely. Not that I wouldn’t expect them to back their Service Manager!

Jeff