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Gathering some information for PDK transmission fault.
Last week son drove PTT to store, when came out said reversed out of park spot, and when shifted into drive it was acting as in neutral. Called me. Told him to turn car off, he did. Restarted and car drove just fine even though transmission fault still stayed on.
I scanned car after he returned, got errors all over the place (99% of them are because car was in sport mode and sport+ pasm). So most of these were tripped since PDK got fault so car was not allowed to have the sport modes.

Anyway, I scanned and the two errors that I saw were shift rod 1 sensor implausible signal, and shift rod 2 implausible signal.
After I cleared the codes, car drove just fine.

Then, couple days ago, took car for a quick battery charge 15 minute drive. Car again was in sport/sport+ suspension, and on way back (guess car warmed up fully by then), stopped at a light. At green, tried to drive but car acted as if it is in neutral.
So I went through the gears from D to P, back to D, back to P. Turned car off. Started car, and car drove perfectly fine then, even transmission fault error disappeared (still have to scan car to see if errors in memory).

So gathering my info. Saw few posts on this.
My battery was very questionable. Since starter went it was suspect last year. Kept it just because i was not sold on it being bad (tested ok). But over last 3 months, car got discharged fully, had to boost,and noticed the hatch on way down gave error, electronics like that on fritz especially if using Burmester at loud levels (son loved to do that and that is when I was noticing batt. issues). So this spurred me take battery today in. Tested and showed not far from bad on tester, but when I looked at one side of battery, it started bulging out.
So off i went spending another couple hundred on AGM battery. Just put it back in, drove car around neighborhood trying to cause issue was could not.

Hoping that is what it is, bad battery. Tomorrow I think I will put car up and check the level of PDK fluid. If it is low, could mean sensors may be heated even more. Saw some oil sweat around PDK pan last oil change. Tightened bolts a little, too cheap to spend another 500 to get new pan/oil (just did PDK fluid change maybe 25k miles ago).
If you have info, let me know. I was so hoping I wont be putting together more DIYs, but seems it was optimistic.

So far, if error comes back, I will need the PDK sensor array (about 650), maybe the harness (quite not convinced it is needed as it only provides physical connection, and if not damaged should be fine (about 200). Then would need the PDK pan (another 300), PDK oil (another 250).
Then I read I will need PDK re-calibration (I could buy that when sensors are replaced, only thing these are solid state sensors, so nothing physical to calibrate, but we will see.

Any info will be greatly appreciated. Car drivable, but I am trying to spare it. After battery change I will try to duplicate issue to see if battery resolved it. FYI, Porsche is the World leader when it comes to making cars that are very sensitive to voltage/current levels when it comes to all its subsystems. 50% of all issues can be traced to weak battery. So I am really really hoping this is it. We shall see.

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As an update, put the car up, to check PDK fluid level, just to make sure it did not leak out to low level or something. Checking level I found it to be full. I did see slight oil sweating around the rear of the PDK oil pan.
After the check, I made sure I torque the pan bolts per FSM. They all appeared to be to spec. I added maybe 1Ftlbs on rear bolts for now.

Then I took the car for driving. In normal mode I could not get the error to come up, but in sport mode, after PDK was at temp, I did get the same transmission fault error (stopped at a store, went in to buy something, came back out, started car, at which time saw the transmission fault again).
Had to stop engine, restart, then stop again, and restart, I think 3 times before error cleared from cluster display. This allowed me to get home. When transmission fault was on, car acted as if it was in neutral, you step on gas and car does not drive.
So looks to me like I will be off to a store to get the sensor pack. I do not think I will need the harness, symptoms point to the sensor(s). These are solid state sensors, so I dont know why I would need a PDK recalibration, as these go into exact position by the way they are bolted to the PDK chassis.
So I wonder if the PDK recalibration will be required. I understand if some sensor which have specific motion may need calibration since each moves slightly different, but these are just ones that look like a stick, you bolt them in with a screw at location, which fits exactly.
Guess we will see. This job looks like will cost - about 650 for sensor pack, plus PDK oil cost (I am sure if I captured old into clean bucket I can reuse since oil is maybe 15 or 20k old), plus PDK oil pan cost. I assume about 1k cost to do myself, From posts others stated, this would be about 5k at dealer. Guess if you want to play with nice toys, you best be prepared to have best wallet for them too.

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Maybe it would be worth to put car up, drain oil into a new bucket, replug the sensor harness after cleaning, and refil to drive.  It is possible connections just stale, but have hard time justifying wiring going bad when it is not in overcurrent situation for long, and not physically damaged.  That is why I suspect sensors, very mildly, connection places, not the wiring itself though.

Advice, as always very appreciated.

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  • 10 months later...

A late response but maybe still useful.
Had same 'transmission fault' a few times. At first it would only take one restart to clear then 2 and a subsequent 'check engine light'. Codes 1731/32 came up. Dealer replaced entire valve body assembly under cpo but said only two solenoids were misbehaving. There is a long thread on Rennlist that describes how to service body and replace ZF solenoids under 'Guide to Repairing a PDK Transmission'.

Sent from my iPhone using Tapatalk

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That's great news!
On my end, PDK worked well for 600 miles after the new valve assembly was put in and then the fault returned and much worse at that. Transmission would get stuck in whatever gear you were in. Once stopped computer showed second gear in D, normal, but transmission couldn't oblige. 5-6 resets later car drives fine but both 'transmission fault' and 'check engine' messages are displayed. Happened 3 times in 7 miles or so.
So now after 4 repair attempts and emails to PCNA and PAG customer support to push things along my P4 will get a new PDK.
Dealer tech said one rod was not registering correctly and they cannot split a PDK to investigate or repair. Porsche won't allow it. Always wondered if the sensors were bad though and why with 1731/32 codes they chose to change out the valve assembly. In any case I'll never know and and this point very happy with Porsches response to this issue. It's taken a little time to get this sorted but I am impressed with their CPO program.

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Good to see they responded well.  Not changing gears, unable to go to drive gear, car not moving while in gear, are all symptoms of the pdk gear shift sensors failure.

Hope you have your car working well asap.

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Me too, I love the vehicle. It's really a unique combo of phenomenal comfort and handling. It loves the twisties as much as cruising down a freeway at good speed. And did anyone say good looks [emoji16]

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Agree.  What I love about my ptt (besides handling, power, braking, interior finish), is the way I can control tire spin with throttle.  Very predictable and repeatable.

You can go into a corner, scrub speed before hand, and accelerate into the curve while controlling the spin.  

That's the kind of control which puts a huge grin on my mug.

Edited by ciaka
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  • 3 weeks later...

A quick update to the PDK saga that my Panamera 4 has been suffering through.

Shortly after replacing the PDK and sending me on my way a presumably happy and relieved customer, the dreaded 'transmission fault' re-appeared :(
Unbelievable was my first thought. Not really, a whole litany of choice words actually....
Fast forward a week and after data was sent to Germany for analysis, the TCU was deemed faulty.
TCU replaced.
Fast forward another few weeks and problem seemingly solved :)

Strange troubleshooting in my opinion:

1- Recalibration
2-New valve assembly (2 valves faulty)
3-Recalibration w/updated software
4-New PDK
5-New TCU

After step 1-4 'transmission fault' came back within days. Original transmission shifted correctly after sufficient off/restart cycles even with 'check engine' & ' transmission fault' messages present.
Porsche dealership said they have never changed out a TCU.

Food for thought.

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  • 1 month later...

To update, my transmission fault turned out to be the shift rod sensors.  Bought new part, took apart the trannie bottom (easy) replaced, recalibrated (need PIWIS2), and car as good as new.  Been done for about 8 months now with no issues.  I havea. detailed DIY for it as well if anyone is getting very similar issue.

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To update, my transmission fault turned out to be the shift rod sensors.  Bought new part, took apart the trannie bottom (easy) replaced, recalibrated (need PIWIS2), and car as good as new.  Been done for about 8 months now with no issues.  I havea. detailed DIY for it as well if anyone is getting very similar issue.
That's great news!!!
What codes were you getting?
Unfortunately for me the situation is not so clear. 
I have basically not driven my car this year! It has now been in the shop for the 7th time for the same 'transmission fault' issue. Latest effort to fix has been 6 weeks.
More parts have been replaced and just recently they 're-threaded' 2 wires through the harness. 
They then drove it around for 280miles and it failed again.
At this point Porsche is looking a data points within the transmission again, which is brand new ! Dealer is out of ideas. Literally.
My brain hurts thinking about this *** backwards troubleshooting and I am confident that I will not be driving this car any time soon and most likely selling it 'as is' after Nov when the cpo runs out.
In the meantime I am attempting to recover some money through courts.
My first and last experience with the brand. 
A sad thing as I really enjoyed this vehicle. 
Porsche makes great vehicles and reliable if you take JD Powers into account but as a small manufacturer seemingly doesn't dedicate sufficient resources to support their dealerships and customers when things are out of the ordinary.
Not sure what to replace such a unique vehicle with, but I'm looking...
Happy Motoring.
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