Anyone seen that before? Search doesn't yield any results. Drove the car yesterday then dropped it off at the garage. Picked it up this morning to drive out east. Went away after two restarts and/or about 90 miles. Car seems fine. Any ideas? It's going in for 12k service on Friday so will post them and see if they can figure it out. TIA.

 

If the battery gets disconnected it's completely normal. Should go away after a few min.

 

Battery hasn't been disconnected. I did switch to snows about two weeks ago. They are 295/30/19 versus stock 305/30/19. Should not be enough to make the differential care since it is less than 1% difference in height based on my calculation. Car driving fine so maybe just a random gremlin since it was about 28 degrees out.

 

I am not sure if it's related, but it sure is suspicious: The ratio of rear to front tire diameter has to maintain a certain ratio or you could damage the differential. You only change rear size? There is a tire calculator on Tire Rack web site I believe that will calculate diameter of tires for you. I vaguely recall some 2-3% increase or decrease will lead to trouble with the Porsche Turbo.

It seems you already know the issue involved. A while back there is a long thread on this; someone was switching to different tires and ran into difficulty -- maybe damaged the differential.

 

Thanks. Yeah that thread was related to a switch to 20s and or 315 rears. Switched both front and rear to Sottorosso 240s and went with 295 rears pursuant to advice from Damon at Tire Rack so I can't imagine that's the issue.

Since it threw that fault presumably the dealer can pick it up and diagnose it. Since the "PTM Failure" message went away I'm hoping that perhaps it was just taken out of it's garage spot in a funky way (it's on one of those lift things in the garage).

 

I've had that message twice, about a year apart. Stopped the car, restart, all is ok. Dealer could never figure it out, never happened with snows. A gremlin I think.