lron City

Hi all,


I own a 2010 Mustang GT, 4.6 L. A couple of days ago, I have replaced the stock 19 inch rims and 245/45/R19 tires, with the following combination:

Front: 18 x 9 inch rims, 255/45/R18,
Rear: 18 x 10 inch rims, 285/40/R18.

I purchased the new rims from American Muscle, with a set of tyre pressure monitors. I mounted all of it together in a shop, inflated all the tires to 2.5 bar.

I enjoyed the ride for a hundred miles or so, but then the tyre indicator on my dashboard started flashing, and on-board computer gave the message: "TYRE PRESSURE MONITOR FAULT".

I have two guesses. Either one of the tyre pressure monitors failed after hundred miles only, or the on-board computer went berserk by the increased pressure in the tires. (Stock wheels where at 2.2 bar, I inflated the new tyres to 2.5 bar).

Has someone a better guess what is going wrong here?


Cheers


lron City

corruptor

Have you tried swapping the wheels back to stock and driving around for 15 miles or so to see if the previous sensors will clear the code?

arabianobsession

The extra inflation might just be enough for your TPMS system to give a warning. Most systems are designed to throw a fault code if the tires are under inflated or over inflated from what pressure is set stock.

lron City

No, I didn't try that and I won't be able to do so soon, 'cos one of the stock tyres is flat. Need to repair it first.

lron City

So, you think it is only the extra pressure which is confusing the on-board computer?

Is it possible to set the default pressure to a different (non-stock) value, or even disable this check altogether?

The only message I am getting from the on-board computer now is "TYRE PRESSURE MONITOR FAULT"

arabianobsession

It is a very real possibility that it could just be a bit too much pressure. The sensors should be able to be reprogrammed to accept a different pressure value.

Doogie65

New sensors require programming and it may have just taken that initial 100 mile drive to get them to trigger the fault. Check with AM as they do carry the tool needed for completing the programming. It is a pretty simple process that only takes a couple minutes.

lron City

Thanks, will do :-)

Er ... by the way, what does AM stands for?

Norm Peterson

I know it's been suggested that the new sensors probably were not trained to the TPMS system.

In a little more detail, if when you start your car it is within range of the stack of tires that you took off (and which still have the original sensors that the TPMS recognizes in them), the TPMS system normally won't register a fault until you've driven a considerable distance (20 miles/30 km or so at least on my '08). On startup, TPMS first pings the sensors just to verify that everything is at least working, and if everything is operational (regardless of exactly where the sensors are or what the tire pressures themselves are) you won't get the 'Fault' message. Once you go past that distance sans trained sensors, you will get the Fault message or indication.

Near as I can tell from running a set of summer wheels/tires with no sensors, you could drive forever without seeing any TPMS FAULT message as long as you drove less than about 30km between each time you started the car up near your old stack of tires. I don't know if having one of the originals go flat would throw a Tire Pressure Low message if you drove away from it soon enough.


A difference of 0.3 bar (about 4 psi) should not be enough to trip the TPMS system. Tires can gain that much pressure from cold just from driving them moderately hard on a hot day.


Norm

Doogie65

AM = American Muscle