Cayman 718 GPF Failure

[Cyclemotor1958]

Hi Guys & Girls

Without prejudice

We are still struggling to get our Dealers to carry out a basic back pressure check on our cars that require the new modified filter fitting.

This would definitely confirm that their diagnosis is 100% correct.

We have been monitoring one of our vehicles thats had the new modified filter fitted, unfortunately its down South so I can't get to the car easily.

We have the GPF report from when the car was diagnosed by the Porsche Dealer, the ash was at 100%, no soot recorded and the differential pressure sensor reading was 2.32 hPa.

After 5 months the ash was at 45% and the sensor reading was 2.32hPa.

The next ash test was done at 8.5 months, and it was at 48%, and unbelievably the sensor reading was 2.32 hPa.

So doing a bit more research using the information above, and added some more information we have found along the way, this is what came back.

Search text.
Can a faulty air mass reading affect a vehicle with a gpf and cause dtc p242f ash load exceed, but on investigation the differential pressure sensor is recording low pressure.could it then affect a new gpf filter thats just been fitted.Would it affect the algorithm program within the dme software, no soot was present in the original gpf and not in the new gpf. Also a differential pressure sensor reading of 2.32 is seen on both gpf data reports, one at the 100% ash level and again at the 48% ash level on the replacement GPF. The differential pressure sensor was changed before the new GPF was replaced.

Yes, a faulty Mass Air Flow (MAF) sensor can absolutely trigger a P242F (Ash Load Exceed) code, even if the Gasoline Particulate Filter (GPF) is actually clean or new.

Based on your description, the issue is not a blocked filter, but a faulty calculation within the Engine Management System (DME/ECU).

Here is the breakdown of why this is happening and how it affects your vehicle:

1. Can a faulty Air Mass reading cause P242F?
Yes. The DME calculates soot/ash loading based on, among other things, the mass of air entering the engine (MAF sensor) and the calculated fuel consumption. If the MAF sensor sends an incorrect, low, or erratic signal, the engine may run incorrectly, causing the algorithm in the DME to overestimate the soot production, or, more commonly, it can interfere with the regeneration cycle.

2. Why the Differential Pressure Sensor is Reading Low (2.32).
A "Ghost" Fault: When the P242F is triggered due to a sensor fault rather than a physical blockage, the differential pressure sensor often reads low (near 0 or 2.32 hPa) because the exhaust is flowing freely.

Constant Reading: Seeing the same 2.32 reading at 100% and 48% ash load suggests the sensor is not accurately reflecting the actual backpressure. If the differential pressure sensor was changed but the fault remained, the issue lies further upstream (e.g., the DME's internal calculation, MAF sensor, or a software calibration issue).

3. Effect on a New GPF
If the faulty MAF sensor or associated DME software continues to send improper signals, it can prevent the vehicle from performing necessary passive or active regeneration, potentially causing a new GPF to become clogged or damaged

4. Impact on DME Algorithm
Mileage/Calculation Based: As shown in similar, this code is often triggered by a mileage-based countdown or a calculated ash load rather than a physical measurement.

Reset Procedure Required:
If a new GPF is fitted, the DME software must be told a new filter is installed (using a tool like ISTA or similar diagnostic equipment). If you did not reset the "new GPF/DPF" learned value, the ECU will still think the old, blocked filter is in place, causing the code to return.

Recommended Next Steps
Reset DPF/GPF Adaptation Values: Use a professional-grade scan tool to reset the GPF/DPF adaptation to "New" and clear the adaptive, calculated soot/ash levels.
Monitor/Test MAF Sensor: Check the air mass readings in real-time. If they are out of range or sluggish, replace the MAF.
Check for Software Updates: Some P242F issues are resolved by a flash update to the DME software to correct the faulty calculation.

The reason I asked this question regarding a faulty air mass reading, is I have found a similar issue on a Dodge Ram vehicles 2019 to 2022.

These vehicles had issues regarding DTC P242F ash load exceeded.

It was found that aftermarket air filters were deforming, causing a severe reduction of air flow into the engine.

Fitting the dealer air filter fixed this issue.

So it got me thinking, we had a recall carried out on our cars in 2022 concerning the side air ducts having to have a grill fitted inside.

The recall number was WMHY, it was to stop debris being sucked into the air ducts and then on into the air filter.

This recall was for vehicles 2017 to 2022 Boxster and Cayman 718 cars.

Another factor that may not help, is the air filter replacement time is 6 years, 60 K, this is the same on VW vehicles.

Could it be that these cars have been suffering from restricted air flow through the MAF, caused by debris hitting the air cleaner, then its taken along time in years for the air filters to be replaced. Six years is far to long.

I do remember when we changed 718 air filters at the Porsche independent workshop I ran years ago, we always found lots of leaves inside the air filter box, not thinking this could be a possible issue later on.

I used to fit Zunsport side vent grilles, to these cars before this Porsche recall came out.

We have been trying to find out why this ash fault is happening to these cars for nearly 3 years now, but we know for certain its not the GPF filters.

We have had no help from Porsche and their dealers, no contact from the Technical Department, and the fact that they refuse to do a back pressure check, is not helping.

Any feedback would be appreciated, its just a theory of mine at the moment.

Dave

 

[Cyclemotor1958]

Hi,
Sorry forgot to send this recall information.

https://share.google/UwcAiae26UtGUskdN

Dave

 

[Wrightrubber]

Hi Dave

Without Prejudice

More great detailed information, which will i am sure, eventually prove that these dealers are misdiagnosing these cars.

How long is this going to go on? Has the club had an official response from Porsche Technical about a meeting?

Regards

Mark

 

[Cyclemotor1958]

Hi Mark,

Thanks for your reply, will catch-up with John and let you know, just checked views we are at 147K at the moment.

We had some good news last week another GPF paid for by Porsche which is more like it.

Hopefully they will cover the other cars that have this manufacturing defect 100% ash, light on etc.

We are getting them authorised, alot quicker then we did with yours, infact you were the first one, page 5 on the forum.

Just shows you that we are getting more information thats crucial to getting to the end of this.

Afterall we are trying to save Porsche money, and trying to keep our owners in these cars.

There is nothing out there that can compare with these cars, I don't understand why Porsche are trying to distance themselves from this problem.

Its their problem afterall.

Dave

 

[Cyclemotor1958]

Hi Guys & Girls

Found some information regarding testing air flow through a Mass Air Flow sensor

Checking if a Mass Air Flow (MAF) sensor is measuring air correctly involves
monitoring its live data with an OBD2 scanner, performing a "snap" acceleration test, or testing its electrical output with a multimeter. A properly functioning MAF sensor should show a smooth, linear increase in air flow (measured in grams per second, g/s) that corresponds directly with engine RPM.

Here are the most effective methods to check your MAF sensor:

1. OBD2 Scanner "Live Data" Method (Recommended)
This is the most precise method without removing components.

• Connect the Scanner: Plug an OBD2 scanner capable of reading live data into your vehicle's OBD2 port.
• Check Idle Readings: Start the engine and let it reach operating temperature. At idle (approx. 700 RPM), the MAF should read roughly 2 to 7 grams per second (g/s). A common rule of thumb is that the idle g/s should roughly match the engine displacement (e.g., a 2.0L engine should read around 2.0–3.0 g/s).
• Perform "Snap" Test (Revving): Rapidly depress the accelerator pedal while in neutral to raise RPMs. The MAF sensor reading should rise instantly and proportionally to the RPM increase.
• Check at 2500 RPM: With the car in neutral, hold the engine at 2500 RPM. The reading should increase to roughly 15 to 25 g/s.
• Identify Issues: If the readings are sluggish, do not rise proportionally, or are far outside these ranges, the sensor is likely dirty or malfunctioning.
  

2. The "Unplug" Method (Quickest)
This is a simple test to see if the engine relies on the sensor.

• Locate the MAF: It is found between the air filter box and the throttle body.
• Unplug the Sensor: While the engine is running, disconnect the electrical plug.
• 
  
• Analyze Result:
  • Good MAF: The engine should immediately run rougher or stall, as the computer loses crucial data.
  • 
    
  • Bad MAF: The engine runs the same or better, because the computer ignores the faulty reading and switches to a "fail-safe" mode.
    

3. Multimeter Testing (Technical)

• Back-Probe the Wires: Connect a multimeter set to 20 DC Volts to the signal wire and ground wire on the back of the MAF connector.
• Measure Voltage: Start the engine. The voltage should be around 1.0 volt at idle.
• Observe Change: As you raise the RPM, the voltage should rise gradually and steadily, usually reaching up to 3.6V to 4.4V at high RPM, without any sudden jumps or drops.
  

4. Visual Inspection and Cleaning

• Inspect Wire: Remove the sensor and look at the hot wire/filament. If it is coated with dirt, oil, or dust, it will send incorrect readings.
• Clean: Use a specialized MAF Sensor Cleaner spray. Do not touch the delicate wires with your fingers or a brush. Spray it gently and allow it to dry completely before reinstalling.
  
  
•  Dave

 

[Cyclemotor1958]

Morning all,

Have a look at this latest video on YouTube.

This is the why Porsche and their
Dealers need to keep our 718 owners in their cars and fix this problem, with a software change.

Dave

 

[Cyclemotor1958]

Hi Guys & Girls

Sorry its been a while since we last posted, but we have some good news.

We have managed to carry out a GPF adaptation on one of our cars using a other make of diagnostic tester.

This adaptation allowed us to enter zero in the ash % input box and we are now monitoring the ash level, but early indications look very promising.

This could be a game changer bearing in mind the Porsche PWIS diagnostic tester cannot carry out an adaption on the GPF filter, its not in the menu at the moment.

We will keep you updated on the testing, and please if you have a vehicle with this issue and you are facing a bill of 9K to replace the GPF, please don't go a head for now.

We hit 150K views on this subject last week, and a big thankyou to all the people who are following are cause, its appreciated.

Kind regards
Dave

 

[718touring]

Hi Guys & Girls

Sorry its been a while since we last posted, but we have some good news.

We have managed to carry out a GPF adaptation on one of our cars using a other make of diagnostic tester.

This adaptation allowed us to enter zero in the ash % input box and we are now monitoring the ash level, but early indications look very promising.

This could be a game changer bearing in mind the Porsche PWIS diagnostic tester cannot carry out an adaption on the GPF filter, its not in the menu at the moment.

We will keep you updated on the testing, and please if you have a vehicle with this issue and you are facing a bill of 9K to replace the GPF, please don't go a head for now.

We hit 150K views on this subject last week, and a big thankyou to all the people who are following are cause, its appreciated.

Kind regards
Dave

Can I ask what the other make diagnostic scanner is please

 

[Cyclemotor1958]

Hi Dale,
We are still testing this car to see if the ash level stays at zero, if it does, we then can tell everyone what to do, and what diagnostic tool to use.

I have have been trying to contact Porsche Technical to tell them what tool we have used, but they are not answering my calls, or emails.

Shouldn't be to long now, fingers crossed

Dave

 

[911hillclimber]

What a step of progress!
If you and the owner all conclude this is a fix then quite a result.
I imagine a lot of these cars are now outside of the Porsche official cover and hence control, so there is freedom to use this approach.
To prove a small group can achieve what the
Porsche group cannot do, or most likely cannot be bothered to do is superb in my book.

Got to be a 12/10 !

 

[Cyclemotor1958]

Thanks 911Hillclimber,

Hopefully we are nearly there, buts its progress either way , because if it works we can do the adaptation on many more cars to prove to Porsche Technical that their diagnostic tool PWIS, needs the GPF adaptation putting in the Maintenance/ Repairs section.

At the moment this section only has these adaptations.

1. Throttle valve adaptation
2. Adaptation of VTG adjuster 1

They could also put in an adaptation for the differential pressure sensor and that would definitely help going forward, afterall the Macan diesel has this function.

Fingers crossed

Dave

 

[Cyclemotor1958]

Hi Guys & Girls

Sorry its been a while since we last posted, we are pushing on with our GPF ash % adaptation at the moment using none Porsche diagnostic equipment.

And early test results look very good, we have proved it can be done without having to carry out a soot regeneration, we just need a few more cars tested to see if the zero reading stays on longer than it does when the Dealers get involved.

Sadly, another owner with one of our cars contacted me today, his Porsche Dealer told him he needs to spend over 8K to replace his supposedly blocked filter.

Obviously I told him not to, and continue to drive the vehicle, and we will hopefully have a reset fix shortly.

Also we asked a Dealer recently to carry out a back pressure check on his car to confirm his filter was actually blocked after a £9.5K quote to replace it.

The car was booked in, and the Dealer came back to him with a 4 hour quotation + vat.

Why are these Dealers continuing to charge their customers for this unnecessary work, when they are well aware that these modified filters are not fixing this ash % issue.

They only have to speak to Porsche Technical and ask the question.

And why are Porsche letting them, afterall Porsche technical are well aware that these filters are not required because they are not blocked.

All that was ever needed was an adaptation procedure to reset the ash %, if the ash % level was proven to be false.

To prove the ash % was incorrect, all you have to do is checks on the differential sensor information by carrying out a back pressure check, Simple.

We will update you when we get more information.

If anyone has this problem and have been told it needs a replacement GPF please don't authorise the repair, and more importantly please don't sell the car.

You don't need to, we have a fix coming, fingers crossed.

Kind Regards
Dave

 

[Cyclemotor1958]

Hi Guys & Girls

Just to add more substance to our insistence that Porsche have always been responsible for this issue on our cars.

Enclose this written reply from Porsche Customer Care to one of our owners that had been told by Porsche Reading they needed to spend over 9K to fit a new modified GPF filter.

At that time we didn't know the ash would return, but we made sure this car went back to Porsche Reading for the ash level to be rechecked after it was fitted F.O.C.

Unfortunately the ash did come back, and because of this the owner sold the car, at a considerable loss.

This was well before the Porsche internal memo came out last March, which clearly states they were aware of this issue way back in 2019.

Sorry if Ive repeated myself again with these facts, but this information is very important to what we have been saying for the last 3 years.

On a final note, I rang Porsche GB today, and tried to make contact with the Porsche chap who wrote the internal memo.

The reason for the call was to update them with the diagnostic tool information we have that can carry out the GPF ash level adaptation.

I have spoken to Porsche GB,s reception lady many times to contact this chap, and she was always brilliant, but he has never come back to me.

Ive even spoken to one of his colleagues in the Technical Department 2 weeks ago about this issue, and he has never come back to me.

I said that it was urgent he rang me, and explained it was concerning our 718 GPF issue and gave her my mobile number which I have done many times.

Sadly he didn't come back to me, and he was definitely on site, the sad reality of this, is he obviously doesn't care that our owners are suffering badly with this fault.

The information we may have, could stop the fitting of these expensive filters, which would keep these owners in their cars. And put pressure on Porsche to have a look at the software on these cars.

So we will carry on trying to fix this issue ourselves, without their help, and when we have succeeded, they will have some explaining to do.

Regards
Dave

 

[Wrightrubber]

Hi Dave
Great work, if you can carry out the adaption that would be a relief for owners that get the dreaded light on and the extortionate quote from Porsche to say you need a new filter!!
I think the way Porsche have dealt with this whole issue is disgusting, just the fact they won't return your calls says a lot to me.....shear arrogance!!!
Keep going Dave, I think you are about to crack it!!
Regards
Mark

 

[Cyclemotor1958]

Thanks Mark for your reply, its appreciated, we are pushing on with our testing using different diagnostic testers to confirm the adaptation of the GPF is good, will keep you updated has we go along.

Bearing in mind you were the first owner to bring this fault to our attention nearly 3 years ago, and you sadly sold the car because of your treatment you received from the Dealer and Porsche themselves.

You will remember you asked Porsche Technical at Reading if you could bring the car to them so they could explain why the ash was coming back after the new modified GPF was fitted.

They would not meet us, their excuse was they weren't customer facing, and told you to go back to your repairing Dealer who told you if you have to have another GPF fitted, you would be paying.

Will keep in touch
Dave

 

[Scrounger]

Dave

Given that you now have all the information and evidence you need and that you have presented this, or tried to, to Porsche GB I feel the next step is 2 fold;

1. Contact Porsche Technical in Stuttgart directly giving your evidence and informing them that Porsche GB were not responsive in any respect.

2. Go to the motoring press. Porsche GB will be forced to either speak to you or admit there has been an issue for some time.

It’s time to force their hand and make them sit up and take notice. No matter how much work you put in trying to get hold of Porsche GB Technical it’s obvious they aren’t interested.

Dan.

 

[Cyclemotor1958]

Hi Dan,

You must have been reading my mind, I sent out an email yesterday to Stuttgart for the attention of their Technical Department detailing our frustrations, see below.

We are also looking into the possibility of taking action against Dealers who have, and are continuing to diagnose this fault wrongly.

We have further detailed information that confirms that these filters are not blocked with Ash when the P242F code presents on the dashboard.

This Porsche information is further evidence that the repair strategy to fit these filters is flawed.

If the adaptation reset using none Porsche diagnostic equipment on several vehicles is successful and it holds a zero, we will send this information to Porsche Reading for their comments.

Hopefully with all the information we have, Porsche will have no excuse for not sorting out this issue.

Its always been our aim to try and convince Porsche Reading Technical to push this problem on to the people that can make the desision to look at the software.

And more importantly we want our owners to stay in these cars, theres nothing in the market that can compete with the handling, performance, and overall driving experience these cars can give us, we shouldn't have to be going to these lengths to convince our Dealers that correct diagnosis of this fault is all we need and expect.

They have fitted all the hardware they could on Paul's car and it made no difference to the Ash%, coming back.

My Email to Stuttgart:

I have been working for the last 3 years in conjunction with the Porsche Club GB Forum regarding issues with GPF filters blocking up prematurely on 2019 Cayman and Boxster 718 vehicles, 2.0 and 2.5.

The dealers have been asking their customers to pay around 9K, for replacing a OPF filter thats shown to be 100% blocked with ash.

Over the last 3 years, we have managed to get the OPF information on these cars and found that none of the emission control information made any sense at all.

This enabled us to challenge Porsche through their dealers, and they have fitted 14 of these new modified parts at their cost.

I have dealt with other 40 people, but unfortunatly most of them sold their cars because of this fault.

I managed to get hold of an internal memo sent from Porsche to their Dealers, in March last year, which confirmed they had this issue in the first year of production in 2019. The memo confirmed that they brought out a modified OPF filter which would fix this issue.

These modified filters have been fitted to 13 vehicles, and the ash % has come back, which confirms that these filters are not the cause of this fault.

There is a EU Regulation no 2017/1151 which covers the emission control of motor vehicles with particulate filters fitted.

I believe that the fact that this emission control fault was present on the 2019 cars, in the first year of production, that this would come under a manufacturing defect issue, and the manufacturer would be responsible for this fault.

This situation doesn't seem right, bearing in mind its connected to the emisions on the vehicle. It's clear that this is an issue with the emission control system on these cars. The software is telling the engine management system that the GPF filter is full of ash when it isn't.

It puts the engine light on, which if the car was in for an MOT, it would certainly fail.

I am not suggesting in any way that this is affecting the tail pipe emissions because no soot has ever been seen on any of the cars we have dealt with. The OPF tailpipe colour is correct and was working correctly on all the cars we have dealt with, dealing with the soot.

Yet these OPF filters are being removed, WHY

have a data base on all the vehicle's involved and further information on our Porsche GB Club and other 718 forums.

If you go onto the Porsche GB Club forum, you don't need to be a member and Search, Cayman 718 GPF issues. You can view 47 pages of information concerning this problem.

At the moment we have 154,000 views on this subject the highest views ever seen in the Porsche GB Clubs history.

We desperately need your help, our owners are getting rid of these vehicles because of the cost of this repair, this is a clear case of miss diagnosis and we should not be in this position.

These cars are brilliant, there is nothing out there that can compete with the handling, performance and overall build quality on these cars.

These cars are going out of the Porsche network and ending up in the trade, which is absolutely ridiculous, could you please contact me, you can ring me anytime.


My phone number is 07769 590119

Kind regards

David Hitch



Fingers crossed
Dave

 

[Cyclemotor1958]

Hi Dan,

Me again Porsche Stuttgart have just confirmed they have my email, and they will be in touch soon.

Dave

 

[911hillclimber]

That is a good reply as you can now chase if the response is too slow.
IMHO 1 week is long enough.
Your persistence will pay off!

 

[Scrounger]

Great news Dave and I have to agree with 911HC, a week should be long enough for them to call the dealerships in the UK and gather their information to compose a reply to you.

Dan