Do you have to inform the dealership of any known faults with the car you are part exchanging?

Do you have to inform the dealership of any known faults with the car you are part exchanging?
You are only required by law to inform the dealer about any previous accidents that may not have been reported to an insurance company and anything safety related such as missing air bags ect. Things such as leaking power steering and things like that are up to your discretion. The dealer usually will check the car over and fix any problems but remember, you might end up buying a car at a dealer one day with someone else's untold problems.