One problem related to hydraulic power assist steering system has been reported for the 1998 BMW 740. The most recently reported issues are listed below.
The consumer experienced problems with the steering. The steering locked up and the check engine light came on a few minutes later. The consumer went into another lane of traffic, but was able to get the vehicle to the side of the road. The steering wheel started going into a complete circle. The consumer has not contacted the dealer. The vehicle was towed to a repair shop. They checked the power steering system and didn't find a problem. They hooked the vehicle to diagnostic machine and it didn't show any codes. This happened on August 25, 2005. About two weeks before they replaced a pressure hose on the power steering.