wareaglescott

Cranked up the car and the tire pressure warning came on telling me my front right was -4 psi. Scrolled through to the pressure display and fronts both showed 30 psi, rears at 39 just as I set them. Got about 4000 miles on the car. When I brought the car home new they had higher pressures and I reset them then and have had no issues with TPMS at all. Drove the car about 10 miles home and the -4 psi warning stayed there the entire time. Turned the car off and restarted and it is still there.

What do I need to do to clear this?

dkmesa

The computer has 5 settings to determine optimal tire pressure setting.

Comfort setting (lower pressure) (Y/N)
Load setting (higher pressure) (Y/N)

if you have the comfort setting selected and the load setting deselected, it will set the optimal tire pressures at the lowest levels (I believe on my 991.1 it is 30 and 34 or something). The warning light is triggered when your tire pressure falls below (3psi? 5psi?) below the optimal values.

wareaglescott

Yes I understand that. My question arises from the fact that the indicated pressures are exactly the same as I set them 4000 miles ago and have had no issues since then. Why all the sudden now do I have this -4 warning even though the pressure still shows the same and how to I get rid of it?
FWIW I have comfort selected.

Porsche_nuts

Try changing from 19 inch wheels to 20 inch wheels, then back again. You may have to drive it with the opposite size checked for a while before you switch back. I think doing so resets the pressure monitors.

Code

Add 1 psi to the front. From my experience, even in comfort mode, you're on the edge of the warning trigger at 30 psi. Perhaps you're actually at 29.5 - 29.9, but the display is rounding up to 30.

Penn4S

Get your trusty hand gauge out and measure each tire. If one is lower than you had it set for pump it up let the system reset itself and you should be good. This week I got a low pressure warning even though the TPMS was stating it was at the pressures I set. I got my gauge and checked and one of my tires was a bit low. I added air and let the system reset, good to go. The weather has cooled a bit here and that does affect tire pressures.

arter

May also be that one tire was higher than the others when you last reset the pressures.

whiteducktail

My car just had this same issue. I checked and confirmed that the tire pressures were where I set them previously (31/35). The way to clear it was to select "Comfort" mode in the tire pressure settings page. Apparently it was unchecked somehow, recently. As soon as I checked the "Comfort" box, the alarm went away and has not returned. Your tire pressures seem to rest in both regions, however, IIRC, so you may need to adjust your fronts "up" or your rears "down" to satisfy one of the pressure regions (Comfort or Load).

wareaglescott

Thanks for the feedback. I wish I could attribute it to the temps cooling off. We have had the hottest weather we have had all summer the last week. Miserable. haha

wareaglescott

Page 362 of my manual for the C2S comfort fully loaded calls for 31/39 so not sure how that would be in both regions.

I got my gauge out and reset the fronts to 31 and that cleared the problem. Thanks for the feedback everyone.