01 bmw 330i door lock

the door lock switch on this car is not working properly, sometimes it does n sometimes it doesn't. what should i do to check ?

Are you talking about the remote on the key or the centre console switch, if the first is OK, then I suggest a faulty switch. If you can prise out the switch, shut the doors, 2 leads from the switch, one is permanently at ground, ground the other it should sequentially lock and unlock the car, if that works it's the switch if not it's the body control processor and you've unfortunately got a trip to the dealer.

it's the center switch n i'll try taking the switch out to see what happen and get back to u