Even with the method we use in the D40, some codes are retained, so it's not perfect. However, for most codes, it works.
You could try the same routine and see what happens. Make sure you have the radio PIN somewhere, and if you use the tripmeter for fuel mileage, write that down first. You won't lose the odometer data.
Method: remove battery negative lead. Open car door, press brake, close door, reconnect battery negative lead.