Two problems related to steering failed have been reported for the 2003 BMW Z4. The most recently reported issues are listed below.
For several months, my 2003 BMW Z4 has felt like it was slightly stuck in the center position while driving on the freeway or highway. Recently, the steering has failed completely on engine start-up. In other words the car will barely turn. After it happened, I discovered it will work if the ignition is turned off and then re-started. However, the car still sometimes displays the stickiness in the wheel, especially on warmer days. The car will steer but seems to get stuck slightly when the wheel is centered. In searching for a solution online, I discovered that this has been a problem for many cars of this model.
The contact owns a 2003 BMW Z4. The contact stated while driving 65 mph the steering failed and the contact was unable to completely make a turn which caused her to swerve into the next lane. The failure occurred intermittently and the hot weather was a factor. The vehicle was taken to a BMW specialist who located the failure within the steering column. The vehicle was not repaired. The failure mileage was 25,000 and the current mileage was 35,000.