jfort

Still not working
07 C2S

Stupid TPMS says I am -4 pounds. With good gauge I confirm that the tires are just where I want them, 33 front, 37 rear. On the advice of someone else, to get to that point I filled up to 44 pounds and then let down to 33 and 37. Need to fill symbol went off. I reset to summer 19 inches. It says it has to learn. I go for a long drive with that screen on. The tire symbol and the exclamation point go away. All appears to be OK as the TPMS shows 33 and 37. Then I get home and turn off the car and it immediately says I need to add air again. The sensors are less than a year old and have worked fine until last week. Can someone please tell me what I am doing wrong?? Thanks in advance.

WhipE350

And every time it happens it complains about -4lb one or all four?

jfort

I simplified. I have done they reset three times. The -4 shows up on three of the tires one time and two of the tires another time.

jfort

More info: This morning the 997 greets me saying 3 out of 4 wheels are -4. (I am so tired of the yellow flat tire icon and the red exclamation point!) On the pressure screen it says 30 front, 33 rear. Actual pressures with a good gauge are 32 and 37 - about what I want given the temperature will go up 10 degrees today and I'd like to be riding on 33 and 37.

Is this system not smart enough to start or "set" taking my input for the start point? Why is the indicated pressure 3 degrees below the actual pressure?

devioustrap

Do you have another gauge to test?

Not saying you're crazy, but if you have the exact same variance between all 4 sensors and your gauge, I'd be tempted to check that the gauge is accurate. It would be odd for all the sensors to go bad and a failing control module would likely present itself with something weirder than erroring by the same amount on every tire.

jfort

good point. I have two other good digital gauges. I'll check with all three and report back

jaybr

I have a 08 C4 under CPO. My TPMS batteries have 60 months left on all four sensors. I've just started getting -4 on both rear tires when there is 35psi in each when measured with gauge. Fronts are showing 32psi with gauge and no low pressure warning messages. I have an appointment with dealer on Aug 3 to resolve issue. I'm assuming the fix is covered under CPO. I'll let you know what they determine what the problem is and what the fix is afterwards.

OKB

08 with 60 months left. 14 yrs time. Either the sensors have been replaced, or somebodys figuring wrong
My guess is that you need new sensors, both guys need new sensors.
You can go to any tire store and they have a signal strength meter that tells you if the sensor is good or bad

jaybr

The batteries for the sensors showed 65 months left in Nov '16. Also at time of purchase I was advised sensors were replaced in Jan '15. Assuming battery life of 84 months (7 years) for 997.1 TPMS, that tracks with remaining months in Nov '16. Since I'm under warranty, I'll let dealer fix it whatever the cause.

Astur

I had a similar problem with -4 lbs warning and I too wanted 33 & 37 lbs F/R when cold (misnomer here in the Caribbean but...).

Anyway, I inflated my tires to 33-37 and at the TPMS Menu configured it for 2 passengers and 18" summer tires although I'm actually running 19". So far no warning messages and after running for a while TPMS says the pressures are at 35 & 39 which I can live with.

jfort

update: 7/31/17

TPMS shows 33 34 37 37 and needing air warning

confirmatory? readings:

Astro Pneumatic digital on compressor
35.5 35.6 39.1 39.4

Shrader digital (I trust this old gauge. Shows that TPMS is about 1# below)
32.5 34.3 38.2 38.5

Tire Tek analog (new, out of box) essentially the same as Shrader
32.8 34.0 38.5 39

McDaniel Control analog (big gauge for track)
33.1 34.8 39.0 39.2

(of course, third digit on analogs is a visual estimate)

This morning 8/1/17. TPMS says I need air. It shows
29 29 33 33. That is after overnight in garage about 75 degrees

Shrader digital shows (again, TPMS seems to be a pound low if you believe Shrader)
30.9 31.4 35.2 34

I fill to 33.2 33.3 37.1 37.5 on Shrader

TPMS indicates 31 31 34 36 still with warning

I fill to 35.2 35.2 39.2 39.2 using Shrader. Initiate new TPMS setting. Do learn run. Warnings go away. TPMS indicates 33 33 37 37

After a few more interstate miles on sunny 80 degree day, TPMS shows
35 35 39 39 with no warnings.

So, so far for today, it's OK. If it shows warning tomorrow morning I will freak out. It's not even cold out yet.

jaybr

Dealer reset settings...took it for a learn run...warnings gone. Dealer says this is a 977.1 TPMS common problem. 977.2 has improved TPMS

jfort

I drove mine yesterday after resetting the day before. Still OK with no warnings. Also, I found this on another thread about this issue. I apologize for not attributing this to its learned author, but it is helpful in understanding the TPMS:

For my 2006 C2S with 19" wheels it lists pressures as 37F/44R. These are the FULL LOAD target pressures.

My 2006 C2S lists partial load pressures in the owner's manual at 33F/39R. These are the PARTIAL LOAD target pressures.

So pick one target for your car and use it, either full load or partial load. Most cases partial load will be better for you.

You have to tell the car which target pressures you have setup your car with - match the computer to the targets you use. If you run partial load pressures but tell the TPMS system it's full load, then the TPMS system will think you are underfilled by -4 or -5 psi. It's the difference between full load and partial load targets.

997_Toronto

Had the same issue, here's what worked for me...I added air to the tires and the TPMS resolved itself.