PV997

The first one is AWD clutch fluid which is part of the front differential (rear compartment, the transfer case). It holds about 0.95 liters as is due at 60k miles/6 years so this makes sense. Ouch on the price though.

The second one is the PDK transmission fluid (what I refer to as PDK clutch fluid to differentiate it from the PDK gear oil). The PDK only holds slightly over 5 liters when completely dry so I suspect they drained and refilled it twice to use 7 liters. Step 1: drained and replaced the first 3 liters (gets out about 60% of old fluid). Step 2: Ran the car to mix up the fluid, then drained and replaced it again (total fluid replaced = 84% - 60% from the first drain and 60% of the remaining 40% from the second drain). This is probably what they called a "flush" and is not a bad idea though it uses a lot of expensive fluid, particularly at dealership prices. To be clear, this is speculation on my part as it's not called out in the WM as far as I can tell.

sandwedge

I think under filling of PDK fluid is a good guess. Both the service advisor and the tech who worked on my car were gone when I picked up the car and nothing was written up or entered into my service history with the dealership. " Under filled the PDK fluid during service" was probably not something they wanted to announce. Was busy with work at that time and the car is under warranty so didn't follow up for details. The fact that the problem was rectified in such a short time and given how limited the dealerships are in what they're allowed to to with the PDK makes it even more likely that they simply added more fluid and that was it.

Same here. Brake flush is well known but never heard of PDK flush. The only PDK service I've heard of is the 60,000 or 6 year one whichever comes first.

On a side note I should add that the PDK failure on my -09 C4S occurred with just over 40,000 miles on the clock and the car being about 5 1/2 years old. And not a track car. "Electronics related" was all the dealer was able to tell me based on the codes they pulled.

Ironman88

There are two PDK services recommended per the Porsche maintenance schedule -

1) PDK clutch fluid change (at 60k miles or 6 years) and

2) PDK gear oil change (at 120k miles or 12 years).

BucketList

My last service I had the front and rear diff fluids done. The term "PDK gear oil" is a bit misleading. I went back and forth with my indy on this one. He worked as a Porsche mechanic for 12 years before opening his own shop. He was a mechanic for Porsche when they were changing the PDK fluid and filter for a TSB and he said he had done hundreds of PDK oil changes so I will take him at his word. According to him the "PDK clutch oil" (6yr/60K) is also the oil that lubricates and shifts the PDK transmission's gears. The "PDK gear oil" (12yr/120K miles) is really just the rear differential oil. You do rear and the front diff (if AWD) at the same time. The AWD "controller" oil (also 6yr/60k) is really just the electronically controlled transfer case. Took me a while to get this sorted. My car has now had all of the drivetrain oils changed. Not taking any chances/cheap insurance...

PV997

Sorry but despite his CV your Indy is wrong (or misspoke) and this should be corrected so people don't get confused. The PDK transmission has two completely separate fluid sections. The "clutch fluid" section (referred to as transmission fluid in the Porsche WM) uses special ATF that is used only as hydraulic fluid. This fluid is used to engage the clutches and move the gear shift rods. It is not used to lubricate the gears. It is also used for clutch cooling and is controlled by the PDK valve body and the maintenance is 60k miles/6 years for the 997.2 (was changed to 120k miles/12 years for the 991.1).

The PDK gear case compartment (which includes all gear sets and the rear differential) is lubricated by special 75W-90 gear oil in a traditional splash manner just like an MT (i.e. partially filled and gear oil "rides up" the gears to coat everything). In the 997.2 PDK there is no gear oil cooler or pump. In the 991.1 PDK, a gear oil pump and cooler was added. For both the maintenance schedule is 120k miles/12 years.

As you mentioned for AWD models, there is a "transfer case" (aka AWD clutch) in the rear compartment of the front differential. This uses a special Porsche ATF (different from the PDK ATF) with a maintenance of 60k miles/6 years for both the 997.2 and 991.1. The front compartment of the front differential uses the same 75W-90 gear oil as the PDK with maintenance at 120k miles/12 years.

I agree that that it's cheap insurance to replace the 75W-90 gear oil at the same time as the others as no specialized equipment is needed and the gear oil is relatively inexpensive (in the big scheme of things).

Edit: Just a note that the PDK used in the 911/Boxter/Cayman is different from the "PDK" used in the Panamera and the SUVs which could cause some of the confusion when referring to it generically. What I describe above is specific to the 911.

BucketList

OK so I suppose there is some disagreement on whether the clutch oil lubricates any gears. It would be nice to get some clarity on that point from someone who knows. The main point is that there are only 2 fluids, the "clutch oil" and the "gear oil" or "diff oil" which appear to be the same thing with different names. It's interesting that they moved the maintanance schedule for the clutch oil up to 120K on 991.1. I know they added a 3rd radiator to help with PDK cooling (cooler water to the heat exchanger) but you wouldn't think that would be enough to extend the life that much.

robert_ny_cars

Thank you all so much for the details about your vehicles.

I spoke with the service manager today to ask about error codes.
He said we have trouble uploading the error codes to the main Porsche computer system and therefore he can’t tell me what the error codes are.

The car was at the dealer since Monday. Today is Thursday.

He did say that he is working on the theory that it is an electronic component of the PDK and that they are following the checklists to confirm. I believe these are the workshop manual steps that Porsche technicians have to do.

I then asked him if you have no connectivity to PIWIS or Porsche how can you install and restart the new electronics components. You have to use PIWIS to install.

So then he said well we do have an intermittent connection which is improving about an hour per day. He said that in the future the error codes will still be retrievable.

I found that answer to be kind of strange and evasive - that the manager can’t tell me the error codes because there is a connectivity issue but that they could install components when they can briefly connect. Of course they have to know the codes to start the checklist.

Thank you again and I will keep this thread updated.

robert_ny_cars

Will the error codes stay recorded somewhere accessible to OBD2 or only in PIWIS? is there a recommended OBD2 reader that can retrieve them even if they were cleared from the acute area so the dashboard lights go off ?

I would like to share them with the group once I can get them.

The workshop light with the little engine outline came on 2 seconds after starting the car followed by transmission emergency run on Sunday when things failed. Prior to that it was transmission emergency run which cleared upon restart.

PV997

Hey I hear you buddy, Porsche has done everything they can to obfuscate what goes on inside this "magic box", and made very little training material available to the public. It really is amazingly simple despite all of Porsche's smoke and mirrors.

I've attached a couple of papers that you might find interesting. The first one is from ZF (the transmission mfgr) and is a white paper on our transmissions. The second one is from the Porsche 997.2 training material and has good details on the inner workings.

PV997

PDK errors can be read with a Durametric or other Porsche-specific code reader in addition to the PIWIS. They will stay stored unless someone deletes them.

Not sure what to make of their connection story. I've got a PIWIS 2 clone without any connection (since it's unauthorized) and I have no trouble reading codes. They should run a Vehicle Analysis Log (VAL) that will be record of everything currently configured or stored on your car (it's like a 100 pages long). If they grabbed the VAL the error codes will be listed right up at the top.

robert_ny_cars

Just got the info from my girlfriend who took the call from the dealer.
Car will be ready on Wednesday.
Electronic component - control unit failure - will need to be brand new.
Error code: P0700

I saw an earlier post by @PV997 that P0700 is not a PIWIS code but what an OBD scanner would say but oh well, that's what we were told by the dealer. I don't like their excuses about "being unable to upload to the computer system that the service manager uses."

Unrelated but thinking back, I also remember that while standing on the red light and pressing on the brake once it did increase the revs for no reason as if I had touched the gas but I didn't do anything with the gas. There was no fault light at that time.

Glad this will be over soon!

robert_ny_cars

Porscheclubgb lists DME 5.2.2 Porsche trouble code as:

P0700 Tiptronic (CAN transfer box setting implausible) or (Transmission oil temperature above Maximum value)


Carobdcodes website lists it as

Possible causes of OBD code P0700 Porsche
– Shorted or open circuit within transmission control module (TCM) – Failure of transmission control module


As happened in my case and described on carobdcodes website this code led to the engine light - return to workshop being triggered with the exclamation mark as well as the digital display saying saying transmission fault.

I would like to get my own PIWIS clone just to look at the history at what code triggered the Transmission Fault without the engine failure light (resettable by restarting engine) before the complete breakdown on Sunday.

sandwedge

What does this mean? New control unit or a whole new PDK unit? Reason I'm asking of course is that as I've said before, your failure sounds similar to my failure which also involved an electronic component. I was told at that time (about 4 years ago) that to replace electronic components the PDK has to be opened up which at that time was not allowed by PCNA. And there's the reason for full replacement rather than repair, at least at that time.

Maybe your failure is different from mine and involves an electronic component that can be accessed without taking the PDK apart or the dealerships have been given more latitude in terms of what they can and can't do.

robert_ny_cars

Sounds like electronic control unit only. Correct, either the failure is different or they can replace more parts of the PDK now. Of course we will have to see if the problem is fixed once the control unit is replaced.

robert_ny_cars

eBay has the following part for $581 to $1000. Perhaps this is what will get replaced.

Porsche 911 997 PDK Gearbox Transmission Control Unit Module OEM ECU 987 Boxster. Fitted to test part during fault diagnosis. Item not required. Boxed Porsche Part number: 99761827040 ZF Part number: 6058209025 SIEMENS Part number: 5WP54023BC Porsche 911 997 Cayman Boxster 987