I just changed the whole back lights of my bmw x5 to LED lights and now I keep getting "check rear light" pops up.... I checked all lights and bulb work i dont have burned ones ....any ideas why?
I changed the whole set and all lights work..its a 2003 bmw x5 3.0LI sport

the sensor might need to be replaced. this happened in my car. just bring it to the dealer they'll diagnose it very easily

The lamp control module is programmed to expect the regular lights that were previously installed in your vehicle. When you changed them to LED's then the computer system must be re-programmed
(to retrofit) the new lights. The system is still looking for the current and resistance values of the regular lights and thus when it sees instead the LED's it sets a fault.
Bring it to an independent BMW repair shop equipped with programming, or bite the bullet and bring it to a dealer.
And next time that you post a question, please try to include the year and engine displacement of the vehicle.