Power Steering is a hydraulic system that most modern cars have. Power to pressurise the hydraulics is provided by the engine which drives a pump and is connected to it in most cases by a belt. Although some Manufacturers have no dispensed with hydraulic systems and are using motors to help turn the wheels. Others have hybrid systems of both hydraulic and motorised power steering.

The most common problems when the power steering fails is that the belt has snapped or the power steering fluid is leaking. Although there are some other common faults depending on which make of car you have.
 

Hydraulic Power Steering Systems

The symptoms of a power steering failure are of course very easy to identify, the steering will go tight and and feel really heavy.

Our advice would be to pull over as soon as possible, although the power steering may cause the steering wheel to get heavy whilst driving, it shouldn't lock completely. So you should be safe to slowly pull over to one side and even continue driving to a safe location if you are in a unknown area.

To check if the fluid is leaking you can do 2 things, Firstly check to see if their is any fluid stains on the ground. Hydraulic fluid is a slippery oily substance that if spilt on the drive will stay for weeks if not months, so the signs should be easy to spot. The second thing you can do is to keep topping up the power steering fluid and monitor it until it disappears or even starts the power steering working again.
 

The fix for power steering units is pretty simple once you know what it is that has caused it, although some car has have the power steering pump place in hard to get to places that may cost you a lot in garage labour to replace it. The part can quickly be unbolted and replaced without too much trouble once reached.

Electro Hydraulic Power Steering

These systems are sometimes shortened to EHPS and also known as Hybrid Power Steering Systems. It works very similar to the common hydraulic system although the pump is not belt driven it is driven by an electric motor and therefore it has no danger of breaking due to the belt snapping.

Although the Hybrid system can fall pray to problems with your battery and alternator which provides the vehicles power system. So if you are experiencing power steering problems and you have this system, you will need to check your battery and alternator. Problems with your battery and alternator can also show themselves by the car struggling to start and conditions such as the electric windows opening and closing slower than usual.

Manufacturers that use this system include Audi, Citroen, Ford, Mazda, Mini, Peugeot, Seat, Skoda, Suzuki, Toyota and Vauxhall

Electric Power Steering Systems

You are likely to find these types of power steering on the Toyota Prius, Toyota Corrolla, Toyota Rav 4, Suzuki swift and the Peugeot 307. The system does provide the vehicle with improved fuel efficiency as the motors take less enery to turn the wheels, than the highly pressurised belt driven hydraulic pump on other vehicles.

This system does not have any hydraulic fluid, sensors on the car detect movement in the steering wheel and applies power to a single electric motor which is connected to the steering gear or column depending on make. 

The car uses a linkage system should the primary electric motors fail. This will allow the vehicle to still be able to turn if the system cease to work whilst the vehicle is in motion. 

This type of system is usually found on smaller cars although new systems are being built for larger vehicles.

As the system is relatively new it is not yet apparent if there are any common problems to this system.