There have been threads about the TPMS reading a few PSI low but mine not read 3 PSI low, the pressure info reading is also way off:

Here the fronts read 31 PSI (actual is 34 PSI from all 3 of my tire gauges)



Then the pressure info displays uneven differences. Any idea how to correct this without a trip to the dealer?

 

Have you tried resetting your sensors? You can reset them and "relearn" the pressures using the on dash computer.

 

Yeah tried that at least 3 4 times. Didn't help at all.

 

Yeah, mine are of no help at all other than to let you know which corner is flat. Relearning doesn't work either. The same numbers keep coming. I'm actually surprised the system doesn't reflect reality a little more closely.

 

I have the same issue... it was working dead on for the first 5k miles and then pooof...

 

sounds like it's time to take it to the dealer. Let us know what they say.

 

Unfortunately, the TPS are always off by about 2-4 psi
ALmost always on the lower side.

They cannot be calibrated by porsche. They probably come like that from the Manufacturer... so those of us that are LAZY... and let it go lower then recomended have a little cushion of error.
Kinda like Fuel Gauge, when it shows empty, but you know you still have a few miles left in the tank.

So, as long as all 4 are consistently 2-4 below ACTUAL, then you should be fine.

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my sensors are always ~2-3 off the true value, nothing new here - dealership told me it's normal.

 

have the same problem here.

 

I like to run around at 33/39 cold but when the TPM system only sees 30/36 and the 30 triggers the dash light which just bucks the S*^% out of me. I finally today tried setting the tire option to winter tire and then the Pressure Info page only show -1 and -2 F/R and no more f*&king warning lights. Problem solved, no... problem masked.

 

On your 997 TT stock setting should be 37 /42

Since you are running 3-4 lbs less, that's why it's going off.


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My main beef is with the Pressure Info difference being off between left and right front tires, the 37/42 PSI is not being adjusted when "partial load" is selected which should bring the threshold down to 33/39 (or thereabout can't remember for sure from the manual), and the main one is the true reading is another 3 PSI off.

 

Never had a car / been in a car where it was accurate. These devices are in need of major improvements. I always check the pressure at every wash, pretty much weekly, and adjust (and it often needs it). Oddly my Evo held great pressure, as does my Lexus GX.

 

Mine are always 3 less in the front and 4 less in the back.

 

My TPMS was running fine till I changed my tires!

In fact, up until I changed my 4 tires (for the first time) at 15,5000 miles it was spot on!

Then suddenly after the tire change it is always lower by 2~3 psi which is annoying cause the red exclamation mark is always lit up.