Driven by the engine, via a drive belt, the power steering pump pressurizes the power steering fluid. When the driver turns the steering wheel, a valve opens and closes allowing the pressurized fluid to enter or leave the power cylinder. The fluid causes the assist piston, found in either the power steering rack or power steering gearbox, to move which aides the driver's steering efforts.
The most common problem with the power steering pump is leakage due to wear over time. Once the power steering pump begins to leak, then it looses fluid and will make steering the vehicle difficult.
Most manufacturer factory warranties cover the power steering pump under the bumper-to-bumper coverage. For extended coverage past the expiration of the factory warranty, an extended auto warranty is an option. More comprehensive plans will cover the power steering pump.