My low tyre pressure warning light on my X5 came on, but all tyre pressures are OK? My handbook is in erman, and I can't translete. Help anyone???

Your tire pressure must be the same as listed on the door jam. If you are running your own pressure needs, then they may not be the same as the OE pressure settings. If you are running the listed pressure, then you may have a sensor bad. Have you had your tires adjusted lately, maybe the tech damaged the sensor.

Also, have you tried resetting the sensor?

hi
your tyres should be the same pressure no matter what psi, the system measures the average distance from the wheel arch to the floor, if one of your tyres is down more than the rest the warning signal will come on. if you can't see that your tyre is flat, simply turn your ignition on and press and hold the tyre pressure button above the ashtray and keep holding it until the simbol on the dash disappears, it will first turn yellow and then switch off
good luck

sorry I assume you have an E53....
if you have an e70, then you have to go to the I drive and reset it there