Hi! Thanks for reply. The light sometimes lights up in yellow, and that indicates flat tires. That happened once to me and I could easily locate the flat tire by my eys at that time. However, it lighted up in red recently and I found nothing wrong each time it lighted up. I just reset the sensor by pressing the button for more than 10 seconds and the light turned to yellow and went out. After that, everything went right without problem.

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--2004 E53 X5 4.8is - ECE version; right hand drive; Located in Hong Kong; ext. black sapphire metallic; int. leather black; adaptive dynamic bi-xenon headlights; 16:9 onboard monitor w/o navigation; 20" genuine BMW Y-spoke 214 wheels with Bridgestone Dueler H/P Sport tires; Int. rear view mirror w/ compass.