The most common power steering problems are steering that suddenly feels heavy, a whine or groan when you turn the wheel, fluid leaking under the front of the car, a steering warning light, and steering that feels notchy or uneven from one side to the other. On a hydraulic system, low fluid and a worn pump cause most of these. On an electric system, there is no fluid to check: faults usually come from the motor, the torque sensor, wiring or the battery's voltage.
Heavy steering is not a loss of steering. The car still turns, only with far more effort. That surprise is what makes it dangerous, so if the assist cuts out while driving, slow down and keep both hands on the wheel.
Which kind does your car have?
Older cars and many heavy-duty pickups use hydraulic assist. Nearly all newer cars and many light trucks use electric assist. A few use a hybrid of the two.
| Hydraulic | Electro-hydraulic | Electric (EPS) | |
|---|---|---|---|
| Source of assist | engine-driven pump pushing fluid into the rack | electric motor driving a hydraulic pump | electric motor on the steering column or rack |
| Fluid to check | yes | yes | no |
| Belt-driven | yes | no | no |
| Typical sounds when failing | whine or groan, worse at full lock | pump hum, whine | usually silent; sometimes a clunk or buzz |
| Typical failures | leaks, worn pump, failed hoses, worn rack seals | pump motor, leaks | motor, torque sensor, control module, wiring |
| Warning light | rarely | sometimes | usually |
The quick way to tell: open the hood and look for a small reservoir with a steering wheel symbol or the words "power steering" on the cap. No reservoir usually means electric.
How electric steering works
JTEKT, the company that introduced the first electric power steering system in 1988, lays out the sequence in its EPS product catalog: a torque sensor in the steering shaft measures how hard you are turning the wheel, and a control unit feeds current to the motor based on that signal and the car's speed. That is why electric steering is light in a parking lot and firmer on the freeway. It also only draws power when you steer, which is one reason carmakers moved to it for fuel economy.
Because the system depends on electricity and sensors, some faults look odd. A weak battery or a charging problem can leave the steering heavy right after a cold start. After an alignment or steering repair, some cars need the steering angle sensor reset, or the lane-keeping and stability systems may complain.
Warning signs, by system
Hydraulic:
- Whine that gets louder as you turn toward full lock, often worse on cold mornings
- Groaning or a moan when parking
- Reddish or amber fluid under the front of the engine
- Steering that gets heavy in short bursts, then recovers
- A squeal from the belt on hard turns
- Foamy or dark fluid in the reservoir
Electric:
- A steering or "EPS" warning light, sometimes with a reduced-assist message
- Steering that is suddenly heavy at all speeds
- Assist that feels uneven, lighter turning one way than the other
- A notchy or sticky feel near center
- Steering that becomes heavy after a jump-start or battery change
Checking hydraulic fluid
- 1Park on level ground. Some makers want the engine warm, some cold; the cap or manual will say.
- 2Find the reservoir and wipe the cap clean before opening it, so grit does not fall in.
- 3Read the level on the dipstick or the side of the tank against the marks.
- 4Look at the fluid. It should be clear and evenly colored. Dark, burnt-smelling or foamy fluid points to wear or air in the system.
- 5Top up only with the fluid your owner's manual names. Some systems use a specific power steering fluid, others automatic transmission fluid, and the wrong type can damage seals.
If you need to add fluid more than once, there is a leak. Topping up treats the symptom while the pump runs short.
What usually fails and why
Pumps wear out, and they wear faster when run low on fluid. A pump that whines with a full reservoir is often near the end.
Hoses harden and crack with heat, especially the high-pressure line near the exhaust. A burst hose can drop the fluid in seconds.
Rack seals leak with age, letting fluid escape at the boots on each side of the rack.
Electric motors and sensors tend to fail outright rather than slowly, and they are often replaced as a unit with part of the column or rack. Carmakers have recalled some electric steering systems over sudden loss of assist, so check your VIN on NHTSA's recall lookup if the light comes on.
Heavy steering can also come from causes outside the assist system: badly underinflated front tires, a seized ball joint or a binding steering column. A shake rather than heavy steering is a separate problem, covered in the steering wheel shaking guide.
Power steering checks in Springfield
Blue Rose Auto Care & Repair Services is a Springfield, Oregon auto shop whose ASE-certified technicians take on mechanical repair, and the business dates back to 1994 in Junction City. The shop's page on Blue Rose Auto power steering repair explains when the system needs service, which is handy if your fluid is dark or the pump has started to whine. Blue Rose Auto keeps weekday hours of 8 to 5, plus Saturdays. For the other front-end guides, start at the suspension and steering overview.
