How does Subaru power steering work?
Subaru’s modern vehicles predominantly use electric power steering (EPAS), which uses an electric motor to provide steering assist and a computer to tailor that help based on speed and driver input. Older or specialty models may still use hydraulic power steering, but EPAS is standard in the current lineup.
How Subaru’s electric power steering system operates
In EPAS, an electric motor is mounted on the steering rack or column and is commanded by the EPS control unit to assist the driver’s turning effort. The system gauges the driver’s intent with a torque sensor in the steering shaft and a steering angle sensor that tracks the wheel’s position, then blends that input with data from the vehicle’s speed and other safety sensors. The result is a variable assist curve: more help at low speeds for easy maneuvering and parking, and less assist at higher speeds to maintain steering precision and road feel.
Core hardware that makes this possible includes the following components:
- Electric motor mounted to the steering rack or column (often brushless DC) that provides the actual assist torque.
- Steering torque sensor that measures how hard you are turning and in which direction.
- Steering angle sensor to determine wheel position relative to the steering shaft.
- EPS control unit (ECU) that maps driver input and vehicle data to motor output.
- Vehicle speed sensor and, in many models, additional sensors used by stability systems such as yaw rate or lateral acceleration.
- Power supply from the vehicle’s electrical system (12-volt), with the battery and alternator supporting steady operation.
- Wiring harness and software that integrates EPS with safety systems like Subaru’s Vehicle Dynamics Control (VDC) and EyeSight where equipped.
In practice, this means most driving situations—from tight city streets to highway cruising—benefit from a steering feel that lightens at slow speeds and firms up at speed, while remaining responsive and predictable. The EPS system also communicates with other safety systems, helping to correct oversteer or understeer by adjusting assist or informing the stability control logic.
Driving experience, safety features, and fault handling
The Subaru EPAS setup is designed to deliver consistent steering effort and stability across a wide range of conditions. At low speeds, the system provides more assist to reduce steering effort during parking and maneuvering. At higher speeds, assist is reduced to preserve road feel and precise control. The EPS controller can also cooperate with Subaru’s stability and driver-assistance systems to help maintain safe handling, and it includes fault-detection logic that can either reconfigure to a safe default or alert the driver if a component fails.
Operating modes and safety behavior
- Low-speed or parking scenarios receive enhanced steering assist for easy maneuvering.
- High-speed driving reduces assist to deliver better steering feedback and precision.
- If a fault is detected, the system may enter a safe fallback mode, which can increase steering effort or illuminate warning indicators on the dash.
These dynamics mean drivers may notice subtle differences in steering feel between different Subaru models or model years, depending on calibrations, safety options, and any active driver-assistance features installed on the vehicle.
Hydraulic vs. electric: a brief history for Subaru
Many older Subarus used hydraulic power steering driven by the engine’s accessory belt, with a hydraulic pump supplying fluid pressure to assist steering. In recent years, Subaru and most mainstream automakers have shifted to electric power steering (EPAS) to improve fuel efficiency, reduce parasitic engine drag, and enable tighter integration with electronic safety systems. While hydraulic systems can still be found in some older or specialty models, EPAS is the standard for most current Subaru vehicles.
Maintenance considerations and common issues
EPAS is largely maintenance-free beyond the usual electrical system care. However, a few issues can arise that affect steering feel or warning lights:
- A weak or failing 12-volt battery can reduce steering assist, especially at startup or in cold weather.
- Sensors or the motor in the EPS assembly can develop faults, triggering warning lights and reduced or altered steering assist.
- In older Subarus with hydraulic systems, leaks or degraded fluid can affect steering effort and feel; those systems require different service than EPAS.
If you notice heavier steering, intermittent assist, unusual noises, or warning lights such as a Power Steering or EPS indicator, have the vehicle diagnosed by a qualified technician. EPS issues are generally addressed through sensor or motor replacement, software updates, or, in some cases, battery or electrical system fixes.
Summary
Subaru’s modern steering is built around electric power steering (EPAS), delivering variable assist that adapts to speed and driver input while integrating with electronic stability and driver-assistance systems. While hydraulic power steering is found in older models, EPAS provides efficiency, improved control, and easier maneuvering in daily driving. Understanding the basics of the torque and angle sensors, the motor-driven assist, and the control unit helps explain why steering feel can vary between models and why the system behaves differently under various driving conditions.
