Cayman 718 GPF Failure
- Thread starter Wrightrubber
- Start date
Hi Guys & Girls
Without prejudice
Are Dealers are still insisting that we have to pay for this manufacturing defect on these cars.
Let's, revisit Paul's post last year, that explained how far the Dealer and Porsche had gone to try and fix this Ash issue on his car, even after all these parts had been fitted.
His post went out on the 23rd July last year, page 32, you can have a look yourselves.
This is the text of the post if you can't get on to our forum.
1.
Without Prejudice
Well it’s been at least a month since I last posted and there has been a lot going on so I feel I owe you all an update.
Just as a recap the start of my GPF nightmare started over a year ago after the light we all fear came on after a days driving enjoying my car with my wife.
A week later I had the you need to pay £8 to £9k call to fix your car as the GPF is 100% full.
I am fortunate enough that my GTS Boxster is a 2nd car and only used at weekends for days out and weekends away which normally entails journeys of 40 to 100 miles each way minimum.
I had only had the car since March 2024 and driven around 1200 miles.
So after the normal 3 month arm wrestle my 1st exchange GPF was fitted and I insisted that I didn’t believe this was the root cause and wanted 4 further VAL tests completed over a period of a year which the OPC agreed too otherwise I was going to reject the car.(my car showed the GPF to be 78% full when I purchased it on a 2019 car with 11200 miles from new)
After 500 miles and me logging my journeys it went back in and was at 29% full… we agreed a further period of driving and 300 miles later in Jan 2025 it went back in and was at over 40%.
Like most people it had taken me a long time to find my perfect spec car and I just wanted it fixed.
So jumping forward to July 2025 my car was still in the OPC trying to be fixed after 7 months. I must say at this point the OPC have been fully supportive and we had regular calls and quite a few face to face interactions. I wouldn’t however have the same level of praise for Porsche GB Reading, and TBH there customer interaction and service levels don’t represent a premium brand in my opinion/experience.
Sadly I have now thrown in the towel and rejected my car but continue my journey with Porsche in a 2021 Boxster GTS 4.0..
My old car is still not fixed and as far as I am aware been trailered off to Reading for further diagnosis and testing.
So in summary the following work was completed in the last year.
3 x replacement GPF(2 brand new/1 exchange)
2 x Differential pressure sensors
1 x DME (Computer/Car Brains)
1 x Oil separator
1 x engine strip down and check
1 x replacement turbo
1 x replacement engine
But sadly no software investigations as far as I am aware.
I am sure there are other bits I have missed and as well as a number of live road VAl tests completed.
Lessons to be learnt -
Work with your OPC - unfortunately it feels to me like they have their hands tied and have to follow what they are told to do.. they have all the responsibility and unfortunately none of the power.
Before you buy any modern car don’t just ask about FSH, ask for the VAL report and check the GPF or even DPF report.. if you feel it’s too high compared to the mileage walk away..
I am no expert but based on my experiences my rule of thumb is 1% ash fill for every 1000 miles.
Please feel free to ask questions I will try and help and support and share my knowledge and experience.
On a final note to the Club and your lack of support for you members, for whatever reason…..
Very disappointing and could try a lot harder…
Well there we are, the car was eventually bought back by the Dealer, because they couldn't fix this issue, ash coming back at an unacceptable level.
Hi car never left the workshop, and he never took it home.
Dave
Without prejudice
Are Dealers are still insisting that we have to pay for this manufacturing defect on these cars.
Let's, revisit Paul's post last year, that explained how far the Dealer and Porsche had gone to try and fix this Ash issue on his car, even after all these parts had been fitted.
His post went out on the 23rd July last year, page 32, you can have a look yourselves.
This is the text of the post if you can't get on to our forum.
1.
Without Prejudice
Well it’s been at least a month since I last posted and there has been a lot going on so I feel I owe you all an update.
Just as a recap the start of my GPF nightmare started over a year ago after the light we all fear came on after a days driving enjoying my car with my wife.
A week later I had the you need to pay £8 to £9k call to fix your car as the GPF is 100% full.
I am fortunate enough that my GTS Boxster is a 2nd car and only used at weekends for days out and weekends away which normally entails journeys of 40 to 100 miles each way minimum.
I had only had the car since March 2024 and driven around 1200 miles.
So after the normal 3 month arm wrestle my 1st exchange GPF was fitted and I insisted that I didn’t believe this was the root cause and wanted 4 further VAL tests completed over a period of a year which the OPC agreed too otherwise I was going to reject the car.(my car showed the GPF to be 78% full when I purchased it on a 2019 car with 11200 miles from new)
After 500 miles and me logging my journeys it went back in and was at 29% full… we agreed a further period of driving and 300 miles later in Jan 2025 it went back in and was at over 40%.
Like most people it had taken me a long time to find my perfect spec car and I just wanted it fixed.
So jumping forward to July 2025 my car was still in the OPC trying to be fixed after 7 months. I must say at this point the OPC have been fully supportive and we had regular calls and quite a few face to face interactions. I wouldn’t however have the same level of praise for Porsche GB Reading, and TBH there customer interaction and service levels don’t represent a premium brand in my opinion/experience.
Sadly I have now thrown in the towel and rejected my car but continue my journey with Porsche in a 2021 Boxster GTS 4.0..
My old car is still not fixed and as far as I am aware been trailered off to Reading for further diagnosis and testing.
So in summary the following work was completed in the last year.
3 x replacement GPF(2 brand new/1 exchange)
2 x Differential pressure sensors
1 x DME (Computer/Car Brains)
1 x Oil separator
1 x engine strip down and check
1 x replacement turbo
1 x replacement engine
But sadly no software investigations as far as I am aware.
I am sure there are other bits I have missed and as well as a number of live road VAl tests completed.
Lessons to be learnt -
Work with your OPC - unfortunately it feels to me like they have their hands tied and have to follow what they are told to do.. they have all the responsibility and unfortunately none of the power.
Before you buy any modern car don’t just ask about FSH, ask for the VAL report and check the GPF or even DPF report.. if you feel it’s too high compared to the mileage walk away..
I am no expert but based on my experiences my rule of thumb is 1% ash fill for every 1000 miles.
Please feel free to ask questions I will try and help and support and share my knowledge and experience.
On a final note to the Club and your lack of support for you members, for whatever reason…..
Very disappointing and could try a lot harder…
Well there we are, the car was eventually bought back by the Dealer, because they couldn't fix this issue, ash coming back at an unacceptable level.
Hi car never left the workshop, and he never took it home.
Dave
I wouldn’t hang about Dave. Go straight to the authorities and report your findings. I understand that some may be in negotiations with dealers but they will dig their heels in and eventually start to say no to everything. At least if the issue is logged with the authorities then they are aware of it, and we know how long it takes to do investigation work.
Dan.
Dan.
Was Paul's car resold by the dealer?
Hi Dan, and 911Hillclimber.
We will be speaking to the Trading Standards people regarding the fact that the Dealers are refusing to carry out the correct diagnosis on a vehicle that is showing electronically that the GPF filter is at 100%.
The fact that our Dealers are using this electronic reading to condemn these filters without checking for back pressure is very suspect.
Regarding Paul's old car, yes its been resold, but we do have the original registration number and chassis number, its in our database.
We have at the moment 3 cars that require a new GPF, at a cost of over 9K. We have asked the Dealers to carry out a back pressure check, only one car is booked in, will update you if it gets done.
Enclose this information for your attention, it just highlights the need for more thorough diagnosis when faced with a suspected blocked GPF.
The motor trade recognized diagnostic path for a suspected blocked Gasoline Particulate Filter (GPF), often referred to as a Petrol Particulate Filter (PPF) or Operating Particulate Filter (OPF), focuses on distinguishing between sensor faults and genuine soot/ash accumulation, followed by forced regeneration or replacement. Because GPFs operate at higher temperatures than diesel filters, they often self-regenerate; therefore, a blockage is frequently triggered by short, city-based driving or faulty exhaust pressure sensors.
1. Initial Diagnostic Scan (OBD-II)
2. Physical Inspection
3. Verification & Diagnostic Test
4. Remedy Action
Common Causes & Symptoms in Trade Practice
Points to note:
1. Initial Diagnostic Scan (OBD-11)
We have none of these codes, no pressure, no soot, no sensor codes.
2. Physical Inspection
Because we are not checking for back pressure, the Dealers are assuming that the GPF is definitely blocked.
The only way you can check the GPF core, is to disconnect the rear GPF pipe flange, and check with a very long camera extension.
3. Verification & Diagnostic.
Regarding forced and driving regeneration, this can be done to get rid of soot, but not ash if its physically present in the GPF.
4. Remedy Action
They say they are dealing with Ash, because when they check a GPF thats at 100% and the fault code P242F is present, no soot values are seen electronically.
When these GPF filters or the differential pressure sensors are replaced, they cannot reset the basic setting due to the car not having the adaptation function fitted.
5. Common Causes & Symptoms in Trade Practice
We don't have any issues with reduced power or unusually high fuel consumption.
We do have an issue with the soot regeneration light / message, we never see it, even though the Dealers are saying the GPF is blocked, so were is all the soot going, and why isn't the light / message coming on.
Dont forget we had one of our cars that had covered over 10 thousand miles with the original GPF, that had the DTC P242F, we recorded lots of Ash % checks, and no significant soot was ever recorded. This cars ash values fluctuated between 80 to 100%, over the milege covered.
Regarding the wrong oil being used, this would only be critical if the GPF filters were actually blocked, which they are not.
AND THIS WOULD BE CONFIRMED BY CARRYING OUT A SIMPLE BACK PRESSURE CHECK.
Dave
We will be speaking to the Trading Standards people regarding the fact that the Dealers are refusing to carry out the correct diagnosis on a vehicle that is showing electronically that the GPF filter is at 100%.
The fact that our Dealers are using this electronic reading to condemn these filters without checking for back pressure is very suspect.
Regarding Paul's old car, yes its been resold, but we do have the original registration number and chassis number, its in our database.
We have at the moment 3 cars that require a new GPF, at a cost of over 9K. We have asked the Dealers to carry out a back pressure check, only one car is booked in, will update you if it gets done.
Enclose this information for your attention, it just highlights the need for more thorough diagnosis when faced with a suspected blocked GPF.
The motor trade recognized diagnostic path for a suspected blocked Gasoline Particulate Filter (GPF), often referred to as a Petrol Particulate Filter (PPF) or Operating Particulate Filter (OPF), focuses on distinguishing between sensor faults and genuine soot/ash accumulation, followed by forced regeneration or replacement. Because GPFs operate at higher temperatures than diesel filters, they often self-regenerate; therefore, a blockage is frequently triggered by short, city-based driving or faulty exhaust pressure sensors.
1. Initial Diagnostic Scan (OBD-II)
- Retrieve DTCs:Use a diagnostic scan tool (e.g., Snap-on) to look for GPF-specific codes, such as:
- 34D909: High Soot Load Detected.
- 1A280E / 1A280C: PPF (GPF) Pressure Too High.
- 1A2818: Regeneration Interruption.
- P2452 / P2002: Pressure Sensor Circuit or Efficiency below threshold.
- Live Data Analysis: Check "PPF Backpressure" and "Soot Load" values. A high differential pressure reading at idle or during light load indicates a blockage.
2. Physical Inspection
- Sensor Inspection: Inspect pressure sensor pipes for blockages, damage, or moisture. A clogged or leaking pipe can prevent proper sensor readings, causing the ECU to fail to trigger regeneration.
- Borescope Inspection: If the GPF is suspected to be physically damaged or melted (not just blocked), use a borescope (e.g., Snap-on BK700) through a sensor port to check for honeycomb monolith damage.
3. Verification & Diagnostic Test
- Physical InspectionStationary): Use a diagnostic tool to perform a "Service Regeneration" or "Forced Regeneration" to clear minor to moderate blockages.
- Active Driving Test: Perform a "driving regeneration" procedure, where the vehicle is driven at higher loads to increase exhaust temperature to ~600°C to oxidize the soot.
- Differential Pressure Sensor Check: Using a Mityvac or similar tool, apply pressure to the sensor and verify it matches the Live Data in the diagnostic tool to rule out a faulty sensor.
4. Remedy Action
- Clean/Replace: If the soot load cannot be reduced, the filter may require professional off-car cleaning or replacement.
- Initialisation: If the GPF is replaced, you must perform the "Petrol Particulate Filter: Initial Operation" (functional test) on the diagnostic scanner to reset the soot accumulation counter, or the new filter will instantly trigger a warning light.
Common Causes & Symptoms in Trade Practice
- Symptoms: Warning lights, Reduced power/Limp mode, Start-stop function not working, Unusually high fuel consumption.
- Common Cause: Excessive short trips where the engine never reaches optimum operating temperature.
- Wrong Oil: Using oil that does not meet the manufacturer's low-SAPS (Sulphated Ash, Phosphorus, and Sulphur) specification can permanently block the GPF, making it impossible to regenerate.
Points to note:
1. Initial Diagnostic Scan (OBD-11)
We have none of these codes, no pressure, no soot, no sensor codes.
2. Physical Inspection
Because we are not checking for back pressure, the Dealers are assuming that the GPF is definitely blocked.
The only way you can check the GPF core, is to disconnect the rear GPF pipe flange, and check with a very long camera extension.
3. Verification & Diagnostic.
Regarding forced and driving regeneration, this can be done to get rid of soot, but not ash if its physically present in the GPF.
4. Remedy Action
They say they are dealing with Ash, because when they check a GPF thats at 100% and the fault code P242F is present, no soot values are seen electronically.
When these GPF filters or the differential pressure sensors are replaced, they cannot reset the basic setting due to the car not having the adaptation function fitted.
5. Common Causes & Symptoms in Trade Practice
We don't have any issues with reduced power or unusually high fuel consumption.
We do have an issue with the soot regeneration light / message, we never see it, even though the Dealers are saying the GPF is blocked, so were is all the soot going, and why isn't the light / message coming on.
Dont forget we had one of our cars that had covered over 10 thousand miles with the original GPF, that had the DTC P242F, we recorded lots of Ash % checks, and no significant soot was ever recorded. This cars ash values fluctuated between 80 to 100%, over the milege covered.
Regarding the wrong oil being used, this would only be critical if the GPF filters were actually blocked, which they are not.
AND THIS WOULD BE CONFIRMED BY CARRYING OUT A SIMPLE BACK PRESSURE CHECK.
Dave
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