Not even fifteen years later, but ...

What ever happened with this?

I'm concerned because my 2004 S (tiptronic, not manual; generally as stock as can be other than wheels and exhaust, with no real issues) yesterday threw a "PHC FAILURE" (not "unavailable") error while my daughter was driving it.

I'm away from home, but she was able to find the photo from post #21 above (kind of shows how rare it is, that she happened to find this thread just doing a google search) and said it was like that except for FAILURE instead of UNAVAILABLE, and a red triangle instead of the red circle. It was on for about 4 seconds as she was accelerating away after going through the drive-through. The "!" came on around that time and stayed on until she got home.

Searching the intertubes shows this to be a really rare issue, with not much info on it. And the TSB in post #19 above, is about as close as I have found, but that is explicitly for a manual transmission Cayenne. But also that TSB shows FAILURE, not UNAVAILABLE. But given all the wrong info from Porsche about this rare issue, as shown above, I can't really believe anything, it seems.

Nobody other than me has worked on this car in a few years, so it can't be something like the bit flip error mentioned in post #43.

I have a Foxwell and will see if that shows me anything, but can't do that until I'm home.