I have a 2013 991. Have enjoyed the first 19.5k miles, but am now having an issue. Had to put a new set of rears on the car, and afterwards the PSM started intervening at very low cornering g-forces As low as .45 on the cars meter! I immediately suspected a bad set of tires, so took the first set of pirelli's back for a new set, but no improvement. The local dealer (Carlsen in Palo Alto) cannot find anything wrong with the car, but I am also getting a "check third brake light message" they cannot seem to clear up.

Hoping someone has some idea what is going on. Another bad set of tires? The tire guys damaged something when putting the new tires on? Help, please...

 

Is yours a C4 or C4S possibly? You need to find a better dealership.

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LexVan, it is a plain Carrera S. This is my third 911 and have had good luck with Carlsen over the years... Worried there is some weird gremlin in the stability management. Would seem unlikely to have two bad sets of tires?

 

Sorry. One more bit of info that might be helpful. On a couple of occasions when this has happened it felt mid-corner as if the outside rear of the car squatted down and then the PSM came on...

 

Does the dealership acknowledge a problem? If you are getting a warning light then this should be able to show up on diagnostics. If they find that then they need to correct. It is possible for two bad set of tyres but not likely.

 

The brake fault light shows in the diagnostics, but the stability management coming on is not something that shows up in the diagnostics. They have not duplicated the problem because they have only driven it around the dealership. They need to get it on a winding road which I am going to try to make them do.

 

How many miles on the new rubber? Maybe the mold release just needs to scrub off??Matched tires all corners???

 

LexVan, not many miles on the current set, but prob a few hundred. Put over a thousand on first set before replacing them. Problem persisted. And, yes, the tires are the original equipment spec'd for the car. So, unfortunately, do not think either of these issues is the problem.

 

Rears are N-spec? Fronts as well?

 

Correct. They are the right tires.

 

Most likely a bad ground back there somewhere, common to the third brake light and traction control wiring. At a minimum the dealer should have pulled the engine covers and inspected every ground lug in sight, then removed the rear wheels and carried out the same inspection with the car on a lift.

 

Are you sure they are exactly the same as your front tires? And how many miles do you have on the rears now?

 

If this is what happened- and in that order- then it would just about have to be the tires. It is consistent with what happens with mismatched tires. I know you're saying they're exactly the same. Well, they were manufactured a couple years apart. They may be different enough to be causing your problem. This would also explain why you had the same problem with the first set of "bad" tires.

Fortunately there is an easy fix: replace the fronts.

 

Switch to PSS

 

Chuck911, did not think about the lapse of time. Maybe worth throwing a new set of fronts on the car...thanks.