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Cayman 718 GPF Failure

Morning Jeff,
Sorry I didn't answer your question, yes I checked with Porsche parts last year on what sensors are fitted to the exhaust.
And a RF sensor is not used, actually my latest owner with a GPF failure sent me his Val report last night.
It shows his differential pressure sensor was reading -1.24, we have not seen this before.
And a calculated temperature in the filter T255 of 969.31.
This is unbelievable, the car hadn't had a regeneration carried out before or durring the diagnostic test.
We will be checking out the sensor function, and will keep you updated with our findings.
Regards
Dave
 
Morning again,

Just made a blunder, realised these temperatures were measured in Fahrenheit not Celsius on the tester used.
So we have T251 upstream temp of 80.42 degrees C and in filter T255 temp of 520.72 degrees C.
These has usual, are wrong, we will be checking these with a lazer temperature gun to confirm when the car goes back in.
Sorry
Dave
 
Thanks Dave.

Once again some silly differential pressure and temperature values there, although I suppose an in-filter temperature of 520 degrees C is a possibility for satisfactory operation of the cat converter?

Have any owners actually challenged the dealers’ workshop managers to explain such values? It seems that the workshops just recommend a GPF replacement based upon the [computed?] ash level without reference to the underlying data?

Jeff
 
Hi Jeff

Without Prejudice

Thanks for the feedback,

On this subject of exhaust temperature values, I have just gone through 11 Val reports on vehicles that either may require, or have been fitted with new GPF filters, to find any common repetitive issues.

Out of the 11 reports with an ash loading from between 84% to 100%, 8 had very low temperatures on the T251 exhaust gas temperature upstream of filter recorded.

Listed below are these readings recorded.

Upstream T251 In filter T255 Calculated (low to high) in degrees C

8.91 381.60
15.73 129.29
18.16 222.04
18.79 391.16
18.98 287.35
21.35 241.73
24.41 331.54
80.42 520.72

As a guide, one of our vehicles that recently had a new GPF filter fitted, had these good figures, T251 356.04 and T255 351.91 degrees C.

Unfortunately the car had only covered around 2,000 miles, and the oil / ash level was already at 38%, very worrying.
We need to fix these cars before this car needs another filter.

Good even temperatures, this is more like it, after all we are looking at the exhaust temperatures from the front of the GPF to the rear of the GPF.

So what's happening with these temperature calculations, well we have recently fitted a new differential pressure sensor to one of the above vehicles and it added 330.75 degrees C on to the upstream T251 temperature reading.

Brilliant you would say, so we are now looking at the control of the GPF and checking the cars data against our own measurements.

We will be looking at the following items below.

1.The actual exhaust in and out temperatures on the car, using a lazer temperature gun

2. Checking for exhaust back pressure, using a vacuum gauge, either connected to the inlet manifold, or using a exhaust back pressure gauge.
We need to rule out any possible interference from the sports exhaust when its in the quiet mode, reference the recent article.
When a GPF is removed, check the colour of the ash on the core, it is usually light brown in colour, any oil contamination will be obvious on the core.
Could it also be smoke tested to see if its indeed blocked.

3. More checks on the differential pressure sensors, it seems that all these sensors are reading low,
which is good, because it shows that soot is being dealt with, but they seem to low, and do the readings change with more revs are applied.
One positive is that we have collected quite a few photos of the rear tailpipes on these cars, which are showing a light greyish and brown dusting, this is the ash that's coming out of the exhaust.

4. We need to figure out how the ash load is calculated, as you would expect higher readings from the pressure sensor, when the Oil / ash load is at 100%

Recently found some info regarding a VAG instruction for removing clogged particulate matter, using high revs, then coming off the gas for long periods, just letting the vehicle slow under its own steam.
This creates a vacuum in the GPF, sucking up matter up and away from the core and making it airborne
Pressing the throttle again and rapidly increasing revs, expels any burnt ash that's not got a hold yet.

Could Porsche Readings technical department contact us with any advice, to save us time in trying to solve this problem ourselves, we didn't build the car, and it shouldn't be our problem, silence is not always good.

We have 14,000 views on this GPF subject at the moment, and counting

You never know

Will keep in touch with our findings

Dave
 
Brilliant work again Dave, learning more everyday about this problem, wouldn't it be great if Porsche would engage with us to explain from their point what is going on., I'm convinced you will get to the bottom of this, keep up the good work.
Regards
Mark
 
Hi Jeff

Without Prejudice

Thanks for the feedback,

On this subject of exhaust temperature values, I have just gone through 11 Val reports on vehicles that either may require, or have been fitted with new GPF filters, to find any common repetitive issues.

Out of the 11 reports with an ash loading from between 84% to 100%, 8 had very low temperatures on the T251 exhaust gas temperature upstream of filter recorded.

Listed below are these readings recorded.

Upstream T251 In filter T255 Calculated (low to high) in degrees C

8.91 381.60
15.73 129.29
18.16 222.04
18.79 391.16
18.98 287.35
21.35 241.73
24.41 331.54
80.42 520.72

As a guide, one of our vehicles that recently had a new GPF filter fitted, had these good figures, T251 356.04 and T255 351.91 degrees C.

Unfortunately the car had only covered around 2,000 miles, and the oil / ash level was already at 38%, very worrying.
We need to fix these cars before this car needs another filter.

Good even temperatures, this is more like it, after all we are looking at the exhaust temperatures from the front of the GPF to the rear of the GPF.

So what's happening with these temperature calculations, well we have recently fitted a new differential pressure sensor to one of the above vehicles and it added 330.75 degrees C on to the upstream T251 temperature reading.

Brilliant you would say, so we are now looking at the control of the GPF and checking the cars data against our own measurements.

We will be looking at the following items below.

1.The actual exhaust in and out temperatures on the car, using a lazer temperature gun

2. Checking for exhaust back pressure, using a vacuum gauge, either connected to the inlet manifold, or using a exhaust back pressure gauge.
We need to rule out any possible interference from the sports exhaust when its in the quiet mode, reference the recent article.
When a GPF is removed, check the colour of the ash on the core, it is usually light brown in colour, any oil contamination will be obvious on the core.
Could it also be smoke tested to see if its indeed blocked.

3. More checks on the differential pressure sensors, it seems that all these sensors are reading low,
which is good, because it shows that soot is being dealt with, but they seem to low, and do the readings change with more revs are applied.
One positive is that we have collected quite a few photos of the rear tailpipes on these cars, which are showing a light greyish and brown dusting, this is the ash that's coming out of the exhaust.

4. We need to figure out how the ash load is calculated, as you would expect higher readings from the pressure sensor, when the Oil / ash load is at 100%

Recently found some info regarding a VAG instruction for removing clogged particulate matter, using high revs, then coming off the gas for long periods, just letting the vehicle slow under its own steam.
This creates a vacuum in the GPF, sucking up matter up and away from the core and making it airborne
Pressing the throttle again and rapidly increasing revs, expels any burnt ash that's not got a hold yet.

Could Porsche Readings technical department contact us with any advice, to save us time in trying to solve this problem ourselves, we didn't build the car, and it shouldn't be our problem, silence is not always good.

We have 14,000 views on this GPF subject at the moment, and counting

You never know

Will keep in touch with our findings

Dave
Hi Dave,

This whole episode reminds me of the post office scandal -

“Porsche tell you you’re the only one “

“And it’s all your fault”. -
Driving style or Oil used

And fundamentally it could all be down to a computing or programming error where an algorithm doesn’t work..

You are our “Mr Bates” 👏👏👏
 
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Hi Guys & Girls,



Another driver of a Cayman 718 contacted me yesterday with a faulty GPF filter, 2019, 15,000 miles on the clock, off we go again.



Without Prejudice,



Further to our investigation regarding the oil / ash and temperature and soot readings we are currently finding on our Porsche Val diagnostic logs.

This may be a possible explanation of the calculated and measured figures we are seeing.

Found some information this weekend regarding the use of an algorithm that can be used to report the loading of gasoline particulate filters.

Vehicle manufactures created this algorithm to see if exhaust temperature sensers could be removed from an exhaust system, and the temperature of the inlet and outlet of the GPF filter could be reconstructed by manipulating this algorithm equation.

They did this by pulling together other information from the engine control system, and with the help of the algorithm, a loading calculation could be monitored by the ECU.

On our GPF system we do not seem to have any exhaust temperature sensors fitted, and the only sensor we have on the GPF is a differential pressure sensor, which provides information to the ECU regarding the soot loading of the filter.

Also regarding the soot values on the Val report readings K211 & K221, they also seem to make no sense at all. On 10 Val reports we looked at the values in K211 soot load calculated, 9 showed zero readings, and the other reading was .39%.

On the readings from K221 soot load measured values, we had 6 zeros and the other 4 readings as follows .78%, 3.14%, 4.72% , 5.49% what’s going on.

A question we need to ask Porsche, have our cars been built with this algorithm in the engine management emission system.

I have researched other manufactures with GPF fitted, and spoken to dealers that use exhaust temperature sensors in their systems, and they are not having to replace the GPF at the moment. But they are having issues with customers that were not aware that this emission device was fitted when they purchased the car. They are now getting to grips with the particulate warning light and its instruction on what to do when it comes on.

On my last post we had a detailed list of eight GPF exhaust calculated temperature readings taken from eight Val reports. They clearly showed low figures on T251 exhaust gas temperature upstream of the filter, which always coincides with the filter showing an oil /ash measured reading of 100%.

We have also established that on two of our vehicles, that have just had a new differential pressure sensors fitted, that over 300 degrees C was added on to the T251 exhaust gas upstream of filters original reading, before the sensors were fitted.

This proves that the calculated upstream exhaust temperatures come from information provided by the differential sensor

It’s easy to check for pressure in the GPF while you are changing the sensor, all you need to is measure the pressure in the GPF by connecting into both the rubber hoses, this will confirm they are not blocked with soot, and confirm if back pressure is present.

We would expect that if a GPF filter was getting blocked with ash to 100%, the differential pressure readings would be a lot higher than we are seeing, and usually differential pressure sensors only monitor the soot values .

So on our GPF system the differential pressure sensor should look after the soot loading, and it also may provide information to the ECU to calculate the ash loading %.

If we are wrong on this point, Porsche could explain to us were this calculation comes from.

Could it be that if an algorithm is used on our cars, it’s not taking into account an ageing, or a faulty reading sensor, that doesn’t trigger a DTC.

On all of our cars that have had a faulty GPF filter diagnosed, no DTC codes for a faulty differential sensor have been recorded.

On any other vehicles fitted with a GPF, these very low readings would show that the soot loading at the time of the test is ok, reporting very little differential pressure.

So the correct information from this sensor is vital to the correcting running of our GPF filters.

And bearing in mind this sensor, we are being told, has been superseded from the original sensor fitted to our cars, could this have been the issue all along.

We have so far not seen any soot loading lights or driver information on these faulty cars, which would inform the driver to carry out a GPF regeneration. This is clearly detailed in the drivers manual, so could it be, that if our cars use an algorithm, this function was not written in.

It seems that generally if a GPF is faulty, you would have signs of soot passing the core, this usually happens when the core either cracks or separates from the exhaust housing allowing soot to pass right through, which would also show a very low pressure sensor reading.

On all of the cars we are dealing with at the moment, no soot seems to be present in the tailpipes, just a light greyish brown deposit, which is the ash.

On our first GPF replacement the owner reported excessive soot in the tail pipes before the new GPF was fitted.

You certainly wouldn’t expect that these filters could be blocked with ash at such low mileages.

I started on this project on October 4th 2023, by contacting the Porsche Club Forum, with information about a premature failure of a AOS on a 2018 Cayman that I thought could contribute to this GPF issue.

I never thought we would be still pushing Porsche and their dealers to sort out this issue, we have managed along the way to save our customers from paying the high cost of replacing the GPF. And we certainly appreciate the contributions from Porsche and their dealers on these repairs.

But I am worried that we are not getting to the bottom of the cause of these failures fast enough.

Thankfully we are not seeing any failures on 2020 onward vehicles at the moment, do these cars have a particulate filter early warning light that’s working.

It’s taken me a very along time to be allowed to speak directly to a Porsche technician about this problem, but a few weeks ago I was involved with conversations with two technicians regarding replacing faulty differential pressure sensors on two of our cars.

With their help, this was a great success, these guys were very enthusiastic about getting to the bottom of this problem, could either of these Porsche service departments be allowed to spend more time in investigating this issue.

It goes without saying if they would like any of the information we have collected along the way, they can certainly have it.

Some more news, we will, in the next few weeks have one of our Cayman 718 cars with a GPF failure, going into an independent garage for us to replace another faulty differential pressure sensor.

We will also have vacuum checks carried on the engine to check for possible exhaust back pressure, and to see if the exhaust is indeed blocked, and temperature checks, and also a vacuum checks on the AOS.

Will keep you all informed of the results.

To conclude our investigations going forward.

I suggest that if you have a 718 Cayman / Boxster 2.0 or 2.5 model year 2019, and the engine light comes on with the message permitted to drive. Go to your local Porsche Dealer, ask them to carry out a diagnostic check on your car, if the DTC P242F (Particulate filter ash load to high) is present, they need to set up a case with Porsche Customer Care.

You will need to ask them for a copy of the diagnostic report on the GPF system, which will show what’s going wrong, you are entitled to see this report if you are paying for the diagnostic check.

After all the research we have carried out and all the Val reports we have seen, it’s quite obvious that something is very wrong.

The fact that none of our drivers of these cars have ever seen the particulate warning light displayed on the dashboard, and nobody has contacted me regarding the reward I offered for sight of this light working, must mean that it isn’t working.

So if this is proven to be the case, this would be classed as a manufacturing defect, which then would make the cars not fit for purpose, bearing in mind this is an emission device.

Just to help us along, I have a email from Porsche Customer Relations regarding on of our cars that confirms that this fault on this car was down to a manufacturing defect.

This issue seems to be forgotten about, when the customer is told that the cost to rectify this fault is usually around £7,500.00. Then when the customer asks what’s caused this fault, the answer is usually, you have.

These are the following reasons for the failure according to the Dealer.

You have put the wrong oil in your car

You must be driving it like Miss daisy

You cannot do half hour journeys in this car

We have checked your Val report, and this shows in detail, your short journeys and all the times it’s been ticking over far to long.

And before you ask, its not covered under your extended Porsche warranty, because we class it as a consumable filter.

So regarding this Extended warranty, there seems to be no reference in the warranty documents to a GPF filter being an excluded part. If its classed as a service item, like an oil filter, it doesn’t appear on any service schedule with regards to replacing it at any given time and mileage, so it cannot be a service item.

The GPF filter is not a separate part, its part of the catalytic Convertor with a part number of P982254400AF, is parts description is Cat. Convertor with particulate filter.

We are building a data base on all these affected cars, so if you have this fault on your car please contact us on the Forum.

I thought you might like to see a Val report on a vehicle that required a new GPF filter, which may make things a little clearer, enclose below

Well that’s enough for now, sorry for going on and on.

Dave
 

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Brilliant work again Dave, you have clearly put a lot of work into this, it's about time Porsche sat up and listened and gave us an explanation for what is going on. People have paid serious money for these cars, with low mileage and serviced by Porsche only to be told early into their ownership you have to pay circa £7500 to fix it., disgraceful.
Regards Mark
 
It is indeed great work Dave. Thank you. It appears that we now have sufficient information to help anyone with a GPF issue to challenge any charge made by Porsche for their replacement. This is all based on the GPF ’blockages’ being the result of a fault elsewhere in the car’s systems. Dave also has various processes to help an OPC or independent to diagnose what is going on.

We believe that if we can win sufficient numbers of cases Porsche will take notice. This thread contains a mix of facts, assumptions and other information from which conclusions have been drawn. They are ultimately informed opinions and, if they wrong, we would be very happy to have them corrected by Porsche. Our objective is to fully understand how these GPF’s are causing CEL’s to appear and to avoid excessive charges to owners.
 
Great work Dave. I echo John’s words. You’ve done a great job and helped many I’m sure. Let’s just hope Porsche sit up and take notice when they have to replace GPFs under warranty. Hopefully they’ll issue a recall notice or is it worth notifying DVSA of the ongoing issue?

Dan.
 
Great work Dave. I echo John’s words. You’ve done a great job and helped many I’m sure. Let’s just hope Porsche sit up and take notice when they have to replace GPFs under warranty. Hopefully they’ll issue a recall notice or is it worth notifying DVSA of the ongoing issue?

Dan.
Unfortunately you can only issue a recall when you know the root cause to the problem and currently their only solution is to replace the filter which clearly based on evidence we have seen is not the answer.
How long before we see a 2020 car have the same problem, if it doesn’t what changed after the initial introduction of the GPF ?
Are we not at a point where the owners club can use some leverage on Porsche GB Reading and support their members who clearly want to find a long term solution for both current and future owners.
In my world nothing is not fixable you just have to have the desire and drive to find a solution.
 
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How long before we see a 2020 car have the same problem, if it doesn’t what changed after the initial introduction of the GPF ?
So far theses specific issues seem to have only affected early 2019 cars, those produced about 9 months after the introduction of the GPF. Dave will correct me if I am wrong, but I don't believe we have had problems with 2020 and later cars. There may be a 'yet' to add to this statement but no evidence so far.

We do know that the AOS and the DPS have both been updated and possibly other components too, but we have no definitive connection between these and the GPF blockages where we can say how Porsche solved the problem (if they did). It may be that these GPF issues only affected that relatively short period of production and that Porsche would just let them work through the system. If the fault were covered under warranty that would be OK. They have done it many times before with different problems. Our priority is to help where members are faced, unfairly, with a large bill.
 
I have no dog in this fight but I have been following the thread with interest and admiration.

I'd like to offer two thoughts:

1. In my view, this is a clear case where the Club could (or should) act in an advocacy role on behalf of its members in using its connections and leverage to raise the issue with Porsche Cars GB (and, potentially, further up the Porsche organisational tree). The structured approach and analysis that has been undertaken and the logical results that have been produced should be sufficient for the Club to feel both justified and confident in taking-on this issue.

2. I think the suggestion made earlier about involving DVSA might have merit. It may be tricky as the failures are not in themselves directly safety related but my experience is that, if sufficient owners act responsibly in reporting a significant issue to DVSA then they are likely to take it up with the OEM (in this case, via the UK importer). It's hard for these organisations to fob-off an enquiry or investigation launched by DVSA.

Just my two-pennies worth of contribution.

Well done with the analysis to date!

James
 
I don’t know why this just popped into my head. Years ago I had a similar issue with a DPF on a relatively new VW. DP sensor was bad and it wasn’t just my car either. Dealer wanted me to pay for a new filter and I had to insist they replaced the sensor beforehand. Sound familiar?
 
While I'm no longer on the Board this does sound like something the Club could and should be raising with Porsche GB. We are after all here for the benefit of our members and have a direct relationship with the importer and manufacturer of the cars we bought and enjoy.

Perhaps a request to put this issue on the next Board Meeting's agenda is in order to highlight the hard work put in so far and see if we can't gain some traction with senior management to try and find a resolution.

I will happily do this if people think it would help.
 
While I'm no longer on the Board this does sound like something the Club could and should be raising with Porsche GB. We are after all here for the benefit of our members and have a direct relationship with the importer and manufacturer of the cars we bought and enjoy.

Perhaps a request to put this issue on the next Board Meeting's agenda is in order to highlight the hard work put in so far and see if we can't gain some traction with senior management to try and find a resolution.

I will happily do this if people think it would help.
100% Agree with this and would be more than happy to support.
 

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