Steering Angle Sensor
An electronic sensor that measures the angle, direction, and speed of steering wheel rotation for stability systems.
The steering angle sensor (SAS) is an electronic sensor mounted within the steering column assembly. It measures the physical position, rotation angle, and speed at which the driver turns the steering wheel, translating this into a digital signal.
This signal is sent to several onboard computers, including the Electronic Stability Control (ESC) and electric power steering (EPS) modules. The ESC system compares the steering angle (where the driver wants to go) with the vehicle's actual path (measured by yaw and wheel speed sensors) to detect understeer or oversteer.
The SAS must be calibrated precisely so that the computer knows where the 'straight-ahead' position is. If the sensor fails or loses its calibration (which can happen after a wheel alignment or steering repair), the stability control and traction control systems will disable.
Common symptoms of a faulty steering angle sensor include an illuminated ESC/traction light, a heavy or stiff steering feel, and diagnostic codes. Calibrating the sensor requires a professional scan tool.