Ok so I have had my 2004 X3 for about 6 months now and ever since it has gotten cold out (we've seen as low as 18 degrees) Every week the light comes on. I immediately checked all the tires... No leak to be found. Upped the pressure to around 35 PSI which I believe it calls for 32 all around. Could this be a sensor malfunction or is it that sensitive that if it hits 29 or lower it will come on?

It could be a sensor malfunction, or it could be the low outside temperatures. I live in San Diego, so I haven't dealt with the issue much, but I know there was a bulletin released stating that low ambient temperatures might cause the tire light to come on, and it's normal, because the pressure in the tires decreases.

I have seen many instances where the tire pressures are all even, but a nail stuck in one of the tires sets the light off. You might want to jack it up and check all of the tires thoroughly, or take it to a shop and have them check 'em for you.

It could be a sensor malfunction, or it could be the low outside temperatures. I live in San Diego, so I haven't dealt with the issue much, but I know there was a bulletin released stating that low ambient temperatures might cause the tire light to come on, and it's normal, because the pressure in the tires decreases.

I have seen many instances where the tire pressures are all even, but a nail stuck in one of the tires sets the light off. You might want to jack it up and check all of the tires thoroughly, or take it to a shop and have them check 'em for you.



Thanks I checked them all thoroughly in my shop at home and found nothing, I even checked the bead on the wheels to make sure Horrigan BMW didn't mess up when mounting them seeing how they fucked up enough by putting cheap touring tires on instead of all seasons.

The first answer seems pretty logical, I'll just monitor the tires til it warms up and it persists then I'll check the sensor.

Have you "Initialized the Flat Tire Monitor?"

The next time it's cold you might try it. Here's your link
http://www.bmwmotorsports.org/pdf/BMW%20X3%20Owners%20Manual%20-%202004.pdf
page 55

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