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997.2 Turbo S PDK stuck in second gear

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Old 10-05-2020, 02:12 PM
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robert_ny_cars
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Unhappy 997.2 Turbo S PDK stuck in second gear

997.2 Turbo S

I started seeing occasional PDK transmission errors and limp home mode with the car stuck in second gear and no reversing ability.

The car was purchased in June 2020 with about 25K miles on it and driven until 30.5K.

This would happen about weekly starting after a mandatory 30K authorized dealer maintenance with PDK flush in August. (I hope that was done properly). It would reset itself after turning the engine off and on and drive normally leading me to think it was the faulty PDK temp sensor.

It behaved just like this post on the GB Porsche forum:

“No recall that I'm aware of, just a well trodden path as far as I was told. I think it would tend to happen as it did for me when the car is up to operating temp, being driven sedately and then you accelerate hard, if the gearbox temp jumps too quickly for the sensor then it generates this issue. I was informed the sensor was redeveloped, hence the repair kit available under warranty. All the info as I remember it, hope this helps.”

PV997
“Early PDK has an issue with faulty crimp on the PDK temp sensor.”

Yesterday, after two days of normal driving, it got stuck in limp home mode in second gear without restarts clearing it. In addition it showed the engine warning light which was not fixed by opening and closing the gas cap. It had to be driven home during which time it stalled on a busy bridge at low speed in second gear but thankfully could be restarted. "Check engine visit workshop" and "transmission emergency run" errors were both active.

It was subsequently flatbed towed to the dealer. I am awaiting what the dealer will say. It is still under the CPO warranty. I read online everything from finicky 997.2 PDK transmissions that were initially frequently replaced by Porsche to Porsche developing a repair kit for the oil sump temperature sensor. Anyway this is a 2012 997.2 manufactured on 11/23/2011 so I would have hoped that these issues would have been resolved by then but I guess not.

From reading the forums, it looks like there is a flowchart the dealers have with a check of the sensor and a few other things before it says to just replace the PDK.

I would love to hear from other drivers of 997.2 about how this was resolved in your cases. I think some Boxsters were afflicted as well. I see that there is an entire thread devoted to enthusiasts purchasing their own PIWIS clones to try to diagnose these issues and there seems to be a design flaw with the temperature sensor in earlier 997s. Or is it that the gear oil should be cooled and it's not as discussed below?

I also see in an older post by PV997 that a Rennlister sold his 997.2 GTS at a loss after the PDK failed.

Also interesting thought from PV997 - is this a design issue? Should the 997.2 PDK have a gear oil cooler?

"
997.2 PDKs only have a fluid cooler for the clutch fluid, there is no cooler for the gear oil section of the transmission. Starting with the 991s, ZF added a cooler to the gear oil section of the transmission. This is somewhat surprising as their original white paper on the transmission said it wasn't needed and there was no plans to do so. They not only have it on the 991 PDK, but also on the 991 7MT gearbox derived from the PDK gearbox. I have not found any official statements on why the gearbox oil cooler was added.

Caymans with early PDKs have an issue with gear oil cooling under tracked conditions but their transmission is rotated 180 deg from that in the 911's. In a Cayman under heavy acceleration the gear oil would pool within the gearbox and starve the differential causing it to overheat. This is a well documented phenomena. There's an aftermarket kit for Caymans to add a gear oil pump and cooler that addresses this. On a 911 however, the transmission is reversed which maybe causes the opposite to happen (gear oil pooling in the differential and perhaps starving the gearbox). I've not seen any documented cases of this but it sounds plausible. It could also be that the configuration of the baffles and shape of the oil chamber only causes the issue in the Cayman/Boxster due to the transmission orientation.

I saw a post somewhere that a guy had sent his gear oil in for analysis and the report stated that the viscosity had dropped ~15% from that of new gear oil. ZF added the gear oil cooler in 2013 and I doubt they would have done this without good reason. The 997.2 gear oil replacement schedule is 120k miles or 12 years which seems really long. It might be a good idea to replace the gear oil more frequently in 997.2's since we don't have an oil cooler, particularly since its easy to do and doesn't require special tools."

I am lucky in this case as the vehicle is still under the certified pre owned warranty.
Old 10-05-2020, 05:57 PM
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Ironman88
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I would suspect that the gremlin is in the electronics.

Old 10-06-2020, 09:14 AM
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Petza914
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This seems like a very similar failure scenario to what @sandwedge experienced with his PDK failure. Progressively more frequent "PDK run failure" messages until finally it locked up and wouldn't change gears. They replaced his complete unit. Seems like we're seeing a few more of these threads recently, which I guess makes sense as the transmissions accumulate more miles and we get into the upslope of the normal bathtub curve for any mechanical component or assembly, but a major component failure that costs $15k to replace at 30k miles really isn't acceptable.

The other GTS failure I think you were referring to was in Bronz's car, which happened shortly after he had just replaced the motor due to bore scoring, which is quite infrequent in the .2 motors, so he got the one-two punch with his car and not surprising that he gave up on it and sold it after spending about $40k or more in repairs / replacements.
Old 10-06-2020, 09:58 AM
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robert_ny_cars
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It's at the dealer now. I'm anxiously awaiting to hear what the service rep will have to say, but thankfully it should be covered under CPO insurance which is for 2 years from this June. We got the car in June 2020 at around 25K miles and took trips for 5K miles this summer. Sometimes we would accelerate but nothing abusive and we didn't track the car. The total number of launch control starts over these few months was less than 10. I never turned off PSM. I have not used the Sport Plus button for over a month. I really tried to be respectful of this car's age and not go too crazy with it. I wanted it to last as long as possible. The feeling when driving it is incredible. Even at speeds, there is no vibration and it feels glued to the road.

Interestingly enough, I had a beautiful anniversary dinner with my girlfriend on Friday 10/2, we visited my parents on 10/3, and it stopped working well on 10/4. At least the car was there for me flawlessly during these important moments. Imagine what would have happened if it failed just before my anniversary dinner or if it had to be towed from my parents' driveway. It persevered during these moments without any error messages and I'm thankful for that.

The driveway is on an incline. I drove up to get to the house and backed out to get to the street, without scraping anything. The poster on the GB forum said that he had error messages after parking on a downslope. Perhaps there is some type of fluid sensor that goes crazy when one does that or part that was about to fail that finally comes loose with inclination. If it matters, I was moving the rear spoiler up and down before the failure lol.

The transmission can be replaced now, but the question is what to do after the CPO warranty expires. As @Petza914 mentioned about @sandwedge , PDKs can fail. It is an 8 year old car and maybe there are some rubber pieces that age over time as @PV997 discussed extensively. The problem is that Porsche does not allow even simple repairs to the PDK transmission and wants complete replacements. Perhaps one can swap in a manual transmission when mine will fail a second time out of warranty, but who knows if the on board computer would allow the engine to run with a manual. Does any one know if the 997.2 Turbo S had a manual option? From a quick google search it looks like it did. If the computer is hard wired for PDK only, I am stuck paying a 15K PDK replacement fee every 8 years.
Old 10-06-2020, 10:10 AM
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I looked up @sandwedge - same thing like with our car. Transmission emergency run light with come on a few times and vanish after restart about a month before refusing to shift out of second gear.

Maybe we will look into that Fidelity Platinum Warranty.

We have the Sport Chrono package and don't know how to utilize it well, but oh well right now it can't be used lol.

Do we know if @David350 had only the temperature sensor fail or complete PDK failure?
Old 10-06-2020, 10:11 AM
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Petza914
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Your car definitely had a MT option - only the 991.1 GT3 eliminated that choice and then they brought it back for the 991.2 GT3 due to demand, which actually made 991.1 GT3 cars with PDKs drop a bit. However, I doubt that's a simple conversion from PDK to MT. I personally would not own a PDK equipped car without an aftermarket warranty, but you can get a Fidelity one or similar once your CPO time is up, plus you'll likely have a relatively new transmission by then too.
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Old 10-06-2020, 10:28 AM
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Hi Robert - Please make sure you post the error codes the dealer pulls up as that will help the community better understand the issue. If you are getting a temp warning it could be a false unless it corresponds to high stress conditions such as tracking. If is is a faulty temp sensor it's relatively easy to replace and doesn't require transmission removal. The gear oil cooler hypothesis you mentioned is speculation on my part, and a possible explanation for the failure of a specific sensor (distance sensor) within the gear case. These seem to fail more often in hot weather based on the reports people have posted. All of these faults will have very specific codes as a symptom.

One thing the transmission control unit (TCU) does is disable all sorts of PDK functions in response to a fault. Presumably this is done to prevent further damage, but it makes the PDK seem much more broken than it really is. Relatively benign faults such as an intermittent temp sensor or a system communication glitch will often result in the PDK being stuck in a single gear even though there is nothing wrong with the shifting mechanism (which is why it clears after restarting). There are literally dozens of obscure fault conditions that the TCU will respond to in this fashion.

Please keep us posted and good luck.
Old 10-06-2020, 10:33 AM
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Doug H
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CPO . . . Nuf said. Sorry going through the hassle, but nice you are covered and will have a loaner car while they fix it.
Old 10-06-2020, 10:48 AM
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PV997
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Originally Posted by robert_ny_cars
I am stuck paying a 15K PDK replacement fee every 8 years.
PDK failures are rare, there are several examples with well over 100k miles on this forum. Issues that do pop up are almost always electrical/hydraulic issues and virtually never mechanical issues such as bearings or synchros. The gear case is nearly identical to the MT used in the 991.1 as it was developed by ZF for both the PDK and MT use. Of those electrical/hydraulic issues, the temp sensors and valve body solenoids can be easily replaced without removing the transmission. The pressure sensors can also be easily replaced but they require transmission removal. There is a sensor inside the gear case that Porsche refuses to make available. This is a problem but several of us are working on a repair process that replaces the internal electronics within the failed sensor (which we have identified and are readily available). The transmission control unit and gear shift sender are easily accessible outside of the PDK itself and cost only ~$700 each (these cause many of the issues reported, not the transmission.)

Bottom line, the PDK is very reliable and much of it is repairable in the unlikely event of a failure.

If you are worried about it then get an aftermarket warranty once your CPO expires. Personally I'm not worried about it and don't have a warranty. I know failures are very rare and how to repair most of the issues that pop up. If it can't be repaired I can DIY a junkyard transmission for ~$8k. There are many options much cheaper than a $20k (parts/labor) replacement from the dealer.

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Old 10-07-2020, 02:28 AM
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sandwedge
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Originally Posted by Petza914
This seems like a very similar failure scenario to what @sandwedge experienced with his PDK failure. Progressively more frequent "PDK run failure" messages until finally it locked up and wouldn't change gears. They replaced his complete unit. Seems like we're seeing a few more of these threads recently, which I guess makes sense as the transmissions accumulate more miles and we get into the upslope of the normal bathtub curve for any mechanical component or assembly, but a major component failure that costs $15k to replace at 30k miles really isn't acceptable.

The other GTS failure I think you were referring to was in Bronz's car, which happened shortly after he had just replaced the motor due to bore scoring, which is quite infrequent in the .2 motors, so he got the one-two punch with his car and not surprising that he gave up on it and sold it after spending about $40k or more in repairs / replacements.
Originally Posted by robert_ny_cars
I looked up @sandwedge - same thing like with our car. Transmission emergency run light with come on a few times and vanish after restart about a month before refusing to shift out of second gear.

Maybe we will look into that Fidelity Platinum Warranty.


We have the Sport Chrono package and don't know how to utilize it well, but oh well right now it can't be used lol.

Do we know if @David350 had only the temperature sensor fail or complete PDK failure?
Robert.....as Petza said, your issues are very similar to what I went through on my -09 C4S with the first generation PDK except I never got the engine warning light like you did. Based on my failure, my opinion from that point on is that once you get the "Transmission Emergency Run" warning, something isn't right and isn't likely to go away or being a fluke. Same warning a second time doesn't do much to boost confidence.

It's been almost 4 years so I'm trying to remember the sequence. I think I had two events with the "Transmission Emergency Run" warning while the transmission still functioned normally. Warning went away after shutting down and restarting. Then the warning came on a third time and the car wouldn't move no matter what gear was selected and no matter how many times I shut down and restarted.

One exception to the above. The day after I had the 60,000 mile PDK service done, I got the warning again and the car went into limp mode. Flatbed back to the dealer where they fixed it in a matter of hours. Never got a good explanation to what the problem was but I'm assuming something got screwed up during the 60K mile service. I've put about 4K miles on the car since then with no issues so maybe that event can be filed away as a fluke rather than some kind of underlying issue signaling bad things ahead.

Despite my frustrating history with the PDK I see it as a marvel of technology and performance but I wouldn't own one without a warranty. Check with with Michael at Mossy Motors in new Orleans. Best pricing on Fidelity policies I've read and heard of so far. His email is: mjourdan@mossymotors.com


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Old 10-07-2020, 10:16 AM
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Originally Posted by sandwedge
One exception to the above. The day after I had the 60,000 mile PDK service done, I got the warning again and the car went into limp mode. Flatbed back to the dealer where they fixed it in a matter of hours. Never got a good explanation to what the problem was but I'm assuming something got screwed up during the 60K mile service. I've put about 4K miles on the car since then with no issues so maybe that event can be filed away as a fluke rather than some kind of underlying issue signaling bad things ahead.
Wow, that is fascinating Sandwedge. I've got a PIWIS and recently replaced my PDK clutch fluid and it went flawlessly, there really isn't anything that can be fouled up. All the PIWIS does is shut off the oil cooler (to help keep the temp correct for the measuring process) and cycle the solenoids to push fluid through all chambers. I wonder if they underfilled the transmission at the service? I did notice that if the filling hose isn't stuck all the way into the small internal hole the fluid can splash back and start dripping out. I had carefully measured the removed fluid and added fluid so I knew it wasn't full yet and figured out the problem. If someone was careless they could be fooled by this and underfill it. That could possibly explain the warning you got if the trans went overtemp.

Anyways, glad it's fine now and things got worked out.
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Old 10-07-2020, 11:52 AM
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I called the dealer again today. No update yet, not even error codes as of now. I will post updates when I can.
Looking back and reviewing above posts, the light did start to turn on only after the 30K mile service at which time the "PDK flush" was done. Does anyone know what that procedure is? I think the dealer unnecessarily messed with the PDK and perhaps underfilled it or touched something by accident that caused the trouble. It sounds like there is something that dealers are doing wrong while performing maintenance as mentioned by @sandwedge Thank you for all the suggestions.
Old 10-07-2020, 12:19 PM
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Doug H
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Originally Posted by robert_ny_cars
I called the dealer again today. No update yet, not even error codes as of now. I will post updates when I can.
Looking back and reviewing above posts, the light did start to turn on only after the 30K mile service at which time the "PDK flush" was done. Does anyone know what that procedure is? I think the dealer unnecessarily messed with the PDK and perhaps underfilled it or touched something by accident that caused the trouble. It sounds like there is something that dealers are doing wrong while performing maintenance as mentioned by @sandwedge Thank you for all the suggestions.
Doesn't really matter whether dealer error or just a coincidence, your covered by CPO and get a free loaner while they replace if the transmission needs to be replaced. I would not chase the Sandwedge rabbit hole on blaming dealer for your situation since you have CPO coverage. You are just going to make YOUR situation more complicated running with this dealer error theought process which likely lacks any validity.

FWIW, I have had around 10 pdks since 2011 and put perhaps 20k miles a year on just mine and perhaps 10k miles per year on my wife's 2 pdk cars. I have had no pdk issues. I would only get a warranty if the warranty was below $3,000 and would self insure if anything above that. So far, the only extended warranty or after market warranty issue I have had arise was a trunk release switch so my after market warranties have been a total waste of money over the years.
Old 10-07-2020, 12:56 PM
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PV997
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Originally Posted by robert_ny_cars
I called the dealer again today. No update yet, not even error codes as of now. I will post updates when I can.
Looking back and reviewing above posts, the light did start to turn on only after the 30K mile service at which time the "PDK flush" was done. Does anyone know what that procedure is? I think the dealer unnecessarily messed with the PDK and perhaps underfilled it or touched something by accident that caused the trouble. It sounds like there is something that dealers are doing wrong while performing maintenance as mentioned by @sandwedge Thank you for all the suggestions.
First off, I agree with Doug's advice to let the dealership do their thing since it's CPO and they've got the car. I don't quite share his confidence in their competence but we all have our opinions and experiences. It's their problem to fix and I'm sure they'll get it sorted out. The codes are mainly for my own curiosity as we unravel the mysteries of the PDK.

I've never heard the term "PDK flush" used in any official sense, and the workshop manual doesn't have a procedure for it. There is a PDK "change ATF" procedure along with a "checking ATF" procedure. This is a drain and fill of the PDK clutch fluid and is called out at 60k miles/6 years for the 997.2. Although the PDK holds about 5 liters of clutch fluid, the procedure only replaces about 3 liters as fluid remains in the cooler, valve body, clutches, and shifting mechanism during the process. If the pan is dropped more will come out, maybe another 0.5 liters. A PIWIS is used as part of the topping off process as explained in the WM "checking ATF" procedure.

There is also a gear oil compartment in the PDK that has it's own drain and fill procedure. This is very straight-forward and doesn't require a PIWIS. This procedure isn't called out until 120k miles/12 years on the 997.2 so it's unlikely they did this unless there were issues. Your receipt should show what was done from the fluids used. The clutch fluid uses Porsche PDK ATF and the gear compartment uses specific 75W-90 gear oil.

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Old 10-07-2020, 01:11 PM
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Receipt from the 30K service in August (this was a different dealer actually due to closer geographic proximity)
I guess they put together pieces of the 30K service by mileage but also due to time since it's a 2012 vehicle.
---
Transmission service. Customer requests transmission service. PDK Oil change due to time. Performed PDK service.
Transfer Case Concern. All wheel drive controller service due to time. AWS Oil change due to time. Performed all wheel drive controller service.

Qty 1: part 000-043-305-40 Transmission oil Front (looks like this is Pentosin FFL-3 PDK transmission fluid or similar - this was a Penske owned dealer so likely Pennzoil) $78.71
Qty 7: part 000-043-305-13 Transmission oil - P $36.03*7=$252.21


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