[fpena944]

Went on a quick errand and when I got back in my Cayman the instrument panel told me there was an ABS, PSM, and PDK failure. I freaked out a bit but it did say that I can still drive but just to be careful. Since I was only about a mile from home I hurried back but the whole time the car kept misfiring badly.

Hooked up the Durametric and got all of the following codes:

P1700
C1600
P1800
P0600
U0418
P1990
P199A
7010
2125
a221
a008
a016

Since it was a cold and miserable day and everything lit up at once I chalked it up as an anomaly, cleared the codes and the car went back to normal again.

Then this morning it did it again. So now I know something is going on. I started looking up all of the potential causes and found different solutions like battery replacement, brake switch, ABS sensor, bad coils, and even bad PDK itself.

Went to my dad's and hooked it up to his Snap-On diagnostic and this time we got a misfire on cylinder #6. Cleared codes again and in seconds the same misfire.

So I just ordered new coils and plugs. Hopefully this will do the trick but if any of you have observed similar symptoms, let me know what you did to resolve them.

Parts arrive later this week so by this weekend I should know if this solved the issue.

[N_Jay]

Start with a new battery before you drive yourself crazy.

[fpena944]

Start with a new battery before you drive yourself crazy.

We tested the battery and it checked out in terms of voltage and amperage.

Also it was dated August 2022 so replaced right when I bought the car.

[XR4Tim]

Lots of possibilities, but I would say that a bad coil is most likely. Let us know if that doesn't fix it.

[worf]

Agree with -^XR4Tim. Replace the plugs and coil packs first.

[fpena944]

Lots of possibilities, but I would say that a bad cool is most likely. Let us know if that doesn't fix it.

Agree with -^XR4Tim. Replace the plugs and coil packs first.

I just hit 38k miles, seems a bit low in miles to experience this type of failure though, right?

[N_Jay]

Start with a new battery before you drive yourself crazy.

We tested the battery and it checked out in terms of voltage and amperage.

Also it was dated August 2022 so replaced right when I bought the car.

Then double check all the battery cable and grounds.
VAG cars are notorious for multiple unrelated fault codes when there are battery/grounding issues.

[worf]

I just hit 38k miles, seems a bit low in miles to experience this type of failure though, right?

No. (*) And it’s 10 years old. Time is not quite as effective as cycles at making stuff die, but it does make stuff die.

@N_Jay has a good point too. Since you just changed the battery and this problem seems to have occurred on the first really cold day? … a loose battery terminal is also a possibility and very easy to check.

(*) The probable lifetime of all manufactured things can be described as a bell curve. Most of the things will live years consistent with the middle of the curve. A few will last forever. A few will die early. Shit happens.

These coils also seem to have, from time-to-time batches with unusually short lifetimes. It seems common for “young” cars that if one coil fails the others have a higher probability of failure ‘cause same batch. Porsche will only replace them one at a time under warranty though. But, anyway, out-of-warranty SOP is to change the lot.

If it bothers you, swap coils side-to-side and see if the misfire moves.

[fpena944]

Coils and plugs come in on Thursday. If this doesn't work then the battery is next!

[N_Jay]

How many dollars in coils and plugs to avoid a $200 battery?


And if it isn't the battery, you can always shelve it till another car needs one.

[fpena944]

How many dollars in coils and plugs to avoid a $200 battery?


And if it isn't the battery, you can always shelve it till another car needs one.

About $300 for the plugs and coils.

The thing is I've had this same failure and similar symptoms on my 996 and the Cayenne. So that's why we were leaning towards that as the solution. But of course if it doesn't fix the problem then at least I have piece of mind that I'm good for quite some time going forward. Since I'm not planning on getting rid of this car any time soon it's a worthwhile investment.

[N_Jay]

Odd that misfires could show in other systems, However that said, I do recall some other car that would show odf errors related to vibration in the drive line due to a misfire.
Can't remember which car it was. Maybe the 2000 A6?

[worf]

Odd that misfires could show in other systems, However that said, I do recall some other car that would show odf errors related to vibration in the drive line due to a misfire.

My CarChick had a similar dysfunction with her ‘14 981S. Misfiring that triggered a cascade of warnings in the MFD. I don’t recall all of them but they were pretty much for everything in the car except for the sunshades.

In her case the issue was clogged injectors causing random misfires.

But, yeah, the 991/981/718 generation really freaks the fuck out with persistent misfires.

Luckily, her 981 freaked out under warranty. And it took many iterations with PCNA’s ‘tech back-office’ to localize it and in the end they just guessed after having directed the swapping of DME, coil packs, variocam actuators, and a bunch of other bits.

[fpena944]

Swapped out all six coils and spark plugs this morning.

The most difficult one was the cylinder closest to the front of the car on the driver's side. There was simply no clearance at all. When I did this on my 996 I removed the mufflers but in this case we just used a number of u-joints, extensions, and a socket. All of the others were done in minutes.

After this we cleared out the error codes and they haven't come back yet. So far so good but I'll give it about a week before I'm convinced nothing else is wrong.

For the record both the coils and the plugs appeared fine from just looking at them. No cracks or other external defects but I know these things can fail internally.

I'll report back soon with an update!

[worf]

The most difficult one was the cylinder closest to the front of the car on the driver's side. There was simply no clearance at all. When I did this on my 996 I removed the mufflers but in this case we just used a number of u-joints, extensions, and a socket.

Yup. That one sucks. It takes as long to do that one as all the other five combined.

Keep us informed.

[N_Jay]

Since the code was for one Cylinder, did you mark that coil?

[fpena944]

Since the code was for one Cylinder, did you mark that coil?

The code came up for cylinder #6.

And yeah once we wrapped up the job then it hit us that we should have labeled which coil came out of #6.

[fpena944]

Been over a week and no additional codes or warning lights have come up.

So it appears that one bad coil on these cars can cause a multitude of errors and scare the crap out of you.

Fingers crossed that this is it. I'll be taking a trip to FL for the Rolex race at the end of this month so that will be the ultimate test but I think we've found the solution.