How do I "Calibrate" the air pressure system when it said low pressure front left/or doesn"t recognised the tire at all. something with a magnet stored by the spare tire (witch i don't have.

If you mean the TPMS tire pressure monitoring system dashboard light, make sure the tire pressure is set according to the decal on the drives door. If that's ok, have a tire store calibrate your tire sensors. If that doesn't help the sensors themselves need to be replaced. The battery in the sensors have a limited lifespan which is the down side to the system. I had to have mine reset after a tire went flat. If it only leaks a little (normal leakage) it seems to clear if you air it up to spec before it gets too low.

My wish is that the dash told which tire was low and would go red if it got below half it's recommended tire pressure. I freak if it comes on at all since I don't know if it's just a pound low or totally flat! Car manufacturers need to improve this system greatly!

First you need to know how the system works. Your factory rims should have magnetic valve stems, thats how the on board computer detects them, the rolling speed of a tire at 32 psi. is different than at say 25 psi. thats how the computer knows it's not at the right pressure. so if you have done anything to change the fact of the special valve stem I told you about such as putting you spare tire on this would be cause of your light being on. cause the spare tire does not have the special valve stem.

I assume this is a Ford vehicle. Start by having the rear axel serviced At the dealership. There is probably metal dust on the magnetic speed sensor, that triggers off of the ring gear inside the axel housing, causing the fault warning lights on the dash. Run an OBDII scan with a print out while at the dealer. Of coarse fix the tire.

Tire pressure monitoring system. Start by checking your tire pressure and set to what the sticker on the drivers side door frame indicates. If this does not turn the light off you will have to re-learn the sensors to the vehicle. This is done by:
reset the tire pressure monitoring system, to do so, you need to get your key fob, and put your ignition key in the ignition, turn it to the accesories position, and simultaneously press the lock and unlock buttons on the key fob. hold them until the car honks the horn.

then take something to let out air in the tires, you need to start with the left front then go to the right front, then the right rear, then the left rear.

start at the left front, drop the pressure in the tire until the horn beeps, -usually takes 8 seconds or so. then repeat on the other tires in the order above.

After you finish with the final tire, the horn will honk again, then you know your done. usually honks 2 times.

and then you can turn the key off, and set your tire pressures.

TIRE PRESSURE MONITOR SYSTEM
The Tire Pressure Monitor System (TPMS) uses radio and sensor technology to check tire pressure levels. If your vehicle has this feature, sensors are mounted on each tire and wheel assembly, except the spare tire. The TPMS sensors monitor the air pressure in your vehicle's tires and transmit tire pressure readings to a receiver located in the vehicle.

The TPMS is designed to alert the driver, if a low tire pressure condition exists. This system also allows the driver to check tire pressure levels using the Driver Information Center (DIC).

When a low tire pressure condition is detected, the TPMS displays the "CHECK TIRE PRESSURE" warning message on the DIC, and at the same time illuminates the low tire pressure warning symbol.

You may notice, during cooler weather conditions, that the tire pressure monitor light, located on the instrument panel cluster, and the "CHECK TIRE PRESSURE" message will appear when the vehicle is first started and then turn off as you start to drive the vehicle. This could be an early indicator that the tire pressures are getting low and need to be inflated to the proper pressure.

Each tire, including the spare (if provided), should be checked monthly when cold and inflated to the inflation pressure recommended by the vehicle manufacturer on the vehicle placard or tire inflation pressure label. (If your vehicle has tires of a different size than the size indicated on the vehicle placard or tire inflation pressure label, you should determine the proper inflation pressure for those tires.)

As an added safety feature, your vehicle has been equipped with a tire pressure monitoring system (TPMS) that illuminates a low tire pressure telltale when one or more of your tires is significantly under-inflated.

Accordingly, when the low tire pressure telltale illuminates, you should stop and check your tires as soon as possible, and inflate them to the proper pressure. Driving on a significantly under-inflated tire causes the tire to overheat and can lead to tire failure. Under-inflation also reduces fuel efficiency and tire tread life, and may affect the vehicle's handling and stopping ability.

Please note that the TPMS is not a substitute for proper tire maintenance, and it is the driver's responsibility to maintain correct tire pressure, even if under-inflation has not reached the level to trigger illumination of the TPMS low tire pressure telltale.

The "CHECK TIRE PRESSURE" warning message and low tire pressure light (telltale) will appear at each ignition cycle until the tires are inflated to the correct inflation pressure.

The Tire and Loading Information label (tire information placard) shows the size of your vehicle's original tires and the correct inflation pressure for your vehicle's tires when they are cold.

Your vehicle's TPMS can alert you about a low tire pressure condition but it does not replace normal tire maintenance.

NOTICE: Do not use a tire sealant if your vehicle has Tire Pressure Monitors. The liquid sealant can damage the tire pressure monitor sensors.

RESETTING THE TPMS IDENTIFICATION CODES
Each TPMS sensor has a unique identification code. Any time you rotate your vehicle's tires or replace one or more of the TPMS sensors, the identification codes will need to be matched to the new tire/wheel position. Each tire/wheel position is matched to a sensor, by increasing or decreasing the tire's air pressure. The sensors are matched to the tire/wheel positions in the following order: LF TIRE (left front tire on the driver's side of the vehicle), RF TIRE (right front tire on the passengers side of the vehicle), RR TIRE (right rear tire on the passengers side of the vehicle), and LR TIRE (left rear tire on the driver's side of the vehicle).

You will have one minute to match the first tire/wheel position, and five minutes overall to match all four tire/wheel positions. If it takes longer than one minute, to match the first tire and wheel, or more than five minutes to match all four tire and wheel positions the matching process stops and you will need to start over.

The TPMS sensor matching process is outlined below:

1. Set the parking brake.
2. Turn the ignition switch to "RUN" with the engine off.
3. Turn the headlamp switch from "OFF" to the parking lamps setting four times within three seconds. A double horn chirp will sound and the TPMS low tire warning light will begin to flash. The double horn chirp and flashing TPMS warning light indicate that the TPMS matching process has started. The TPMS warning light should continue flashing throughout the matching procedure. The "SERVICE TIRE MONITOR" message will be displayed on the Driver Information Center (DIC).
4. Start with the driver's side front tire.
5. Remove the valve cap from the valve cap stem. Activate the TPMS sensor by increasing or decreasing the tire's air pressure for 10 seconds, then stop and listen for a single horn chirp. The single horn chirp should sound within 15 seconds, confirming that the sensor identification code has been matched to this tire and wheel position. If you do not hear the confirming single horn chirp, you will need to start over with Step 1. To let air-pressure out of a tire you can use the pointed end of the valve cap, a pencil-style air pressure gage or a key.
6. Proceed to the passenger's side front tire, and repeat the procedure in Step 5.
7. Proceed to the passenger's side rear tire, and repeat the procedure in Step 5.
8. Proceed to the driver's side rear tire, and repeat the procedure in Step 5.
9. After hearing the confirming horn chirp for the left rear tire, check to see if the TPMS warning light is still flashing. If it is, turn the ignition switch to LOCK to exit the sensor matching process. If the TPMS warning light is not flashing, the five minute time limit has passed and you will need to start the process over beginning with Step 1.
10. Set all four tires to the recommended air pressure level as indicated on the Tire and Loading Information label.
11. Put the valve caps back on the valve stems. The spare tire does not have a TPMS sensor. If you replace one of the road tires with the spare, the "CHECK TIRE PRESSURE" message will be displayed on the DIC screen. This message should go off once you re-install the road tire containing the TPMS sensor. The "SERVICE TIRE MONITOR" message is displayed when the TPMS is malfunctioning. One or more missing or inoperable TPMS sensors will cause the service tire monitor message to be displayed.

Most likely a bad wheel speed sensor or wiring harness issue.

Labatche822,
The process for resetting your Tire Pressure Monitor (TPM) is below.
Good luck, let me know.
Regards.

To reset (calibrate) the system:
1. Turn the ignition switch to RUN.
2. Press the GAGE INFO button on the DIC until
TIRE PRESSURE appears on the display.
3. Press and hold the DIC RESET button for about five
seconds. After five seconds, the display will show
TIRE PRESSURE RESET. If TIRE PRESSURE
RESET does not appear on the display after about
five seconds, see your dealer for service. After you
release the DIC RESET button, TIRE PRESSURE
NORMAL will appear on the display.
The system completes the calibration process during
driving. During the first 10 to 25 miles (15 to 40 km) of
driving, the system will not alert you if a tire is high or
low. After 25 to 100 miles (40 to 160 km), the
system will only alert you about pressure differences of
12 psi (85 kPa) or more. After about 100 miles (160 km)
of driving, the system will alert you if one tire is
10 psi (69 kPa) different from the other three tires.

Look under the steering wheel~way up under the dash there is on some Pontiacs a reset button. It is usually yellow. If this does not work you can try disconnecting the battery to clear the ECM.

From 2005 STS Owners manual:
Each TPM sensor has a unique identification code. Any
time you replace one or more of the TPM sensors,
the identification codes will need to be matched to the
new tire/wheel position. Each tire/wheel position is
matched, to a sensor, by increasing or decreasing the
tire’s air pressure. The sensors are matched, to the
tire/wheel positions, in the following order: left front (LF),
right front (RF), right rear (RR), and left rear (LR).
You will have one minute to match the first tire/wheel
position, and five minutes overall, to match all four
tire/wheel positions. If it takes longer than one minute,
to match the first tire and wheel, or more than five
minutes to match all four tire/wheel positions the
matching process stops and you will need to start over.
The TPM matching process is outlined below:
1. Set the parking brake.
2. Press the push-button ignition switch to OFF/ACC.
3. Using the Keyless Access transmitter, lock and
unlock the vehicle’s doors.
4. Press the lock and unlock buttons, at the same
time, on the Keyless Access transmitter. A single
horn chirp will sound, indicating that the TPM
system is ready, and the sensor matching process
can begin.
5. Start with the left (driver’s side) front tire.
6. Remove the valve cap from the valve stem.
Activate the TPM sensor by increasing or
decreasing the tire’s air pressure for five seconds,
or until a horn chirp sounds. The horn chirp,
which may take up to 30 seconds, confirms that the
sensor identification code has been matched to
this tire position. To decrease the tire’s air-pressure
use the pointy end of the valve cap, a pencil-style
air pressure gage or a key.
7. Proceed to the right (passenger’s side) front tire,
and repeat the procedure in Step 6.
8. Proceed to the right (passenger’s side) rear tire,
and repeat the procedure in Step 6.
9. Proceed to the left (driver’s side) rear tire, and
repeat the procedure in Step 6.
10. After hearing the confirming double horn chirp, for
the left rear tire, exit the matching process by
turning the ignition switch to OFF/ACC.
11. Set all four tires to the recommended air
pressure level as indicated on the tire and loading
information label.
12. Put the valve caps back on the valve stems.

how do reset the sensor