Why Is My Steering Heavy? Power Steering Problems Explained

The quick answer

Heavy steering usually means your power steering is not helping as it should. On older cars with hydraulic power steering, the most common causes are low fluid from a leak, a worn pump or a slipping drive belt. On most modern cars, which use electric power steering, it is usually an electrical fault, a failing sensor or motor, or low battery voltage. Low tyre pressures and seized suspension parts can also make steering feel heavy.

If the steering suddenly goes heavy while you are driving, slow down, pull over when it is safe, and get it checked before carrying on. You can still steer without power assistance, but it takes far more effort, especially at low speed.

Which type of power steering do you have?

Hydraulic power steering uses a pump, normally driven by the engine auxiliary belt, to push fluid through the steering rack. You will usually find a small fluid reservoir under the bonnet with a cap marked with a steering wheel symbol.

Electric power steering, often called EPS or EPAS, uses an electric motor on the steering column or rack instead. There is no fluid to top up. Most cars built in the last decade or so use this type. Some cars use a mix of the two, with an electric pump running a hydraulic system.

Your handbook will tell you which system your car has, and so will a quick look under the bonnet for that reservoir.

Causes on hydraulic systems

Low fluid is the first thing to rule out. Power steering systems are sealed, so if the level is dropping there is a leak somewhere, often from a hose, a pipe union or the seals in the rack. Look for damp patches under the front of the car. Topping up with the correct fluid is only a short-term fix until the leak is repaired.

A worn pump is next. It often whines, especially when you turn the wheel with the car stationary, and the steering may feel heavier when the engine is at tickover. A stretched or cracked auxiliary belt can slip on the pump pulley and cause the same symptoms, sometimes with a squeal on cold mornings.

Running the system low on fluid can damage the pump, so do not ignore a whine or a falling level.

Causes on electric systems

Electric power steering needs a healthy electrical supply. A weak battery, a failing alternator or a poor earth connection can reduce or switch off the assistance, and you may notice the steering go heavy at the same time as other electrical oddities.

Faults in the torque sensor, which tells the system how hard you are turning the wheel, or in the motor or control unit itself, will usually turn on a steering warning light on the dashboard. Many systems also reduce assistance to protect themselves if you hold the steering on full lock for a long time, such as during lots of parking manoeuvres.

Because these are electronic faults, the first step is plugging in diagnostic equipment to read the stored fault codes rather than guessing and swapping parts. Some steering faults also need the system recalibrating after a repair or a battery change, which again needs the right equipment.

Causes that are not the power steering at all

Before blaming the steering system, check your tyre pressures. Soft front tyres make steering noticeably heavier. Wheel alignment that is badly out after hitting a kerb or pothole can also make the steering feel stiff or cause the car to pull.

Worn or seized parts in the steering and suspension, such as ball joints, track rod ends or the top mounts on the front struts, can add friction and make the wheel feel stiff or notchy. These are also MOT items, so they are worth sorting for more than comfort.

If your steering is heavy in one direction but not the other, or only gets heavy after the car has been driven for a while, mention it when you book. Details like that help narrow down the cause quickly.

Getting your steering checked

Heavy steering makes a car harder to control, particularly in an emergency. At MF Autocentre in Walsall we check the fluid, belt and pump on hydraulic systems, read fault codes on electric systems, and inspect the tyres, alignment and suspension so we find the real cause first time.

If your steering feels heavier than it should, call us on 01922 636820 or book online and we will take a look.