One problem related to cooling fan has been reported for the 2004 Audi S4. The most recently reported issues are listed below.
The contact owns a 2004 Audi S4. When the weather was cold and the contact took his foot off of the accelerator, the vehicle would not slow down. The dealer could not duplicate the problem. The current mileage was about 75,000 miles and the failure mileage was less than 5,000 miles. Updated 01/24/08. The brake lights would come on and go off. The rear view mirror fell off. The cooling fan would stay on at all times. The dealer replaced a faulty fan module. Updated.