Avoid buying a car: The pre- approved loan is based on the current status of your existing bank balance. You want to maintain that status and wait to make any financial changes until after you have gotten your loan. Purchase a car can throw a struggle into your home buying plans. Your loan pre-approval was based on the state of your credit and your debt load at the time of pre-approval before you bought a car. Adding the debt that the car purchases will bring may make you unable to get the loan for your home.