TPMS issue on a 2009 997.2

So this goes into the no-good-deed-goes-unpunished file.
I was in the process of doing an oil change on my wife’s new S.
I planned on doing a DIY with some perty pictures for the board.
To facilitate the photos I took off the rear wheels and rolled them outside for a cleaning session.
The oil change was unremarkable, (watch for upcoming DIY),
BUT
When I put everything together and went for a test drive, I got an error message to the effect of, “You put new wheels on? My computer brain is confused.”

This was followed by continuing messages of, “you have two rear flat tires, STOP DRIVING!”.

We pulled out the manual and followed the steps to let the TPM system re-learn the wheels / tires / pressures. After many iterations of following the manual and driving to let it re-learn, the error message just tells me that we only have ONE flat rear tire.
Sigh, that's progress.
The pressure display indicates between 0 and -4 psi for the four wheels.

My question is, Do any of you have a technique to set the TPMS brain?
Something that does not involve a trip to the dealer?

Thanks

Craig

 

First try taking the car for a drive - I found that the system can take up to 30 minutes or 40+ miles to relearn. Let us know what happens.

 

Ok, so for the one wheel indicating a (presumably COLD) tire pressure of -4psi, that is 4 pounds BELOW the level it should be. What are the PSI readings on those 4 tires cold, taken from the valve on the outside?

I would check to see what the tire pressure is for the tire indicating -4 psi.

My tires are at +2 psi around ... so they are 2 pounds too high, with the TPMS system set to 'partial load' (since only I drive it). No issues for me, and that is pretty much dead on with what the manual says the cold pressure should be for partial load on 18" rubber.

 

Unfortunately, your 09 may operate a lot differently than my 06 TPMS. I have no problems with mine. BUT, one of the significant issues that I see coming up seems to be with what you are choosing for display. Many seem to like a differential pressure up on display, i.e., +4, +2, +1, +0, etc.) while I select absolute TP, i.e., 33, 33, 39, 39. For some reason the "you've got a flat tyre" alert seems to trigger quicker with the differential pressure display up.

I have gone so far as to put another set of rims on (with no TPMS senders) and drive around and NOT get it to whine that it's not getting information. And I haven't even told it what diameter or anything about the new tires.

I always start my mornings cold with 33 and 39 which is lower than reality (if I can trust my different gauges) by about 4 psi.


I wish I could help, but I understand the 09 TPMS has changed substantially.

 

good commentary, as usual

This a.m. I filled the tires to recommended spec, 37 / 44 and heard a report that the brain decided that the tires were NOT flat.
Our display is currently set to differential values.
Prior to wheel removal the display read "absolute" values.

To bolster your opinion that “For some reason the "you've got a flat tyre" alert seems to trigger quicker with the differential pressure display up.”, I offer this data point.

Several weeks ago I lowered TP to 34 / 38 in an effort to get a more “plush” ride for daily commute. Do people really use 44psi in the rear??? My 993 also calls for 44psi and I don’t run over 38 HOT, and AX @ 35 – 36 psi HOT.

Back to the story, the TPMS wasn’t fazed by this lower pressure for several weeks of commuting.
I think that when I removed the wheels, the brain reset to differential mode and gave the “flat tire” warnings.

Now I just need to decipher the manual to see how to go back to “absolute” mode.

Thanks

Craig

 

On the 2009 997.2's the pressure depends on the car. I don't run 44psi on the rear as that is just way to high unless I've got a full car (2 people and their luggage... never gonna be the case).

I don't think the display setting shown in the OBC cluster display matters... or at least it should not.

For tire pressure checking ONLY the differential display is to be used for airing up the tires, as it takes into account the ambient temperature. (cold tires in a 40deg garage will be different than cold tires in a 70deg garage). For the 2009 997.2 the diff readout isn't available unless the car is stationary, I think.

If wheels were not removed and suddenly you did get a reading of 'flat' I'd think the likely reason is the tire pressures were on the borderline of what triggers the 'flat' warning, and a slight loss of pressure (constantly going on anyway) finally pushed the pressure below the threshhold. I think the 'flat tire' warning is triggered by an absolute pressure reading falling below some internally set limit, not by a dynamic effect such as the pressure dropping a few PSI in short order.

Since you pulled the wheels off and the system things new wheels where put on, the system may well also need you to verify the size and type of tire (18 v 19 - summer v winter).

 

I'd probably still just reset the TPMS from the left small stalk. Drive it 5 miles and let it relearn etc...

 

They did change the tire pressure sensors for 2009. From what I was told they now read more frequently for what that is worth.

 

I run the recomended 34/40 although lately it has ben showing the 05-08 recomended 33/39. Anyway, I have removed my wheels and put them back on, got the error messages, reset the TPMS with the stalk menu and drove it around and everything resets.

 

After changing my wheels last weekend (with new TPMS sensors) it took a few drives before it "learned" the new sensors. In the meantime I was getting all sorts of "flat tyre" warnings etc. Mine still reads about 3psi lower than gauge pressures, but at least it is working again.

Funny thing, when I was taking my new rims to the tire shop, the system said it was shutting down because there were too many readings. Obviously, it was picking up the sensors on the 2 wheels I had inside the car.