Electric or hydraulic power steering: what is the difference, and which does my car have?
Hydraulic steering uses an engine-driven pump and fluid pressure to assist the rack; electric steering uses an electric motor controlled by a torque sensor. Hydraulic systems are often praised for feel; electric systems save energy and enable driver-assistance functions. They fail differently, and they cost differently to repair.
Hydraulic (HPS)
A belt-driven pump supplies pressurised fluid to a rotary valve on the steering rack. Turning the wheel opens the valve and pressure helps move the rack. The fluid path transmits road forces back to the driver with little filtering, which is the “feel” enthusiasts mention. The pump runs all the time, costing some power and fuel. Typical faults: fluid leaks from hoses and rack seals, pump whine, noise at full lock, heavy steering when cold or with low fluid.
Electro-hydraulic (EHPS)
A hydraulic rack supplied by an electrically driven pump that runs only as needed. Found on some cars as a transition between the two systems.
Electric (EPS)
An electric motor provides assist on the steering column, on the pinion, or on the rack itself (often via a belt and ball-nut). A torque sensor measures driver effort and a control unit decides how much assist to add, varying it with speed and enabling functions like lane keeping and automated parking. Feel depends on calibration and on how much the system filters road feedback. Some systems reduce assist when they overheat, which can matter in prolonged track use or parking manoeuvres.
Typical faults: torque sensor or position sensor errors, motor or control unit failures, and mechanical rack wear. No fluid to maintain.
Which one do you have
Look for a power steering fluid reservoir and a belt-driven pump in the engine bay (do not confuse it with the brake or clutch reservoir) — that means hydraulic or electro-hydraulic. Its absence, together with features such as lane keeping or park assist, usually means electric. The handbook or a diagnostic scan confirms it.
Cost implications
Hydraulic systems have more maintenance items (fluid, hoses, pump) but many parts can be repaired or resealed individually. Electric racks often integrate motor, sensor and electronics, so a fault can mean replacing the complete unit, plus calibration and coding — generally a larger single repair, less frequently. Diagnosis before replacement matters on both.