Hi, today while i was driving home a got a warning message come up saying CHECK TRAILER LIGHTS, problem is i am not pulling a trailer. when the message is showing the indicators will flash fast when on. then when i brake it tends to go off and all is fine. then while driving it will come back and the go and come back etc. found out that when the error is showing my fog and reverse lights don't work. but all other lights are fine. i parked up and found when the error is not showing everything is fine but then while standing out side the car the fog and reverse light would suddenly go out and the euro would be showing then the message may go after 2 to 10 minutes and fog and reverse lights would come on. did think it could be a loose connection but was doing it while the car was still....... not sure what to check on this .  please help. its on a 05 reg x5 sport. 

Do you have a tow bar and electrical connection fitted?

Hi yes I have the factory fitted tow bar and twin electrics that are covered by the bumper cover. I have never used it myself yet!

I'd imagine that's probably what's causing the problem. Could be a lose connection/faulty relay for this. Would be interesting to know if it's a plug and play BMW kit or if someone has chopped and joined the connections on the rear lights. May be worth having a poke around back there just to see if there is anything obvious...

Also, try plugging in a trailer board just to see if everything is working?