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30 May 2025 (updated) Steering angle sensor: function, failure symptoms, and testing
Contemporary cars have many sensors, here we’ll specifically address your car’s steering angle sensor, what it does, failure symptoms, how to test it, and more.
A steering angle sensor or SAS is a component in a vehicle's electronic stability control (ESC) system that measures the angle and direction of the steering wheel. The SAS provides data to the vehicle's computer system, which uses this information to determine the intended direction of the vehicle and how it should respond to changes in driving conditions. It keeps the vehicle stable and prevents it from skidding or losing control during turns, particularly in emergencies. For example, if the vehicle begins to skid or slide during a turn, the sensor can detect this and send a signal to the ESC system to apply the appropriate brake pressure to individual wheels to help bring the vehicle back under control. This is why you should not drive with a bad steering angle sensor.
Symptoms of a bad steering angle sensor
A faulty steering angle sensor is normally detected by the control unit. An error message is displayed. If the deviation is severe, the car switches to emergency mode and can only be driven very slowly until you reach the nearest garage.
If the faulty steering angle sensor is not detected by the control unit and the traction control light does not light up, dangerous driving situations can occur. A typical sign that something is wrong with the steering is squealing tyres when cornering. A steering angle sensor can be damaged by wear or water penetration. Internal corrosion will interfere with the contacts and interrupt the signal lines. In most cases, however, the contacts are worn to the point where the signals are no longer properly transmitted.
-51%
RIDEX Steering Angle Sensor
Article number: 3252S0009
compared to
RRP
£ 116,00
£ 56,46
Price per item
price incl. 20% VAT, excl. delivery costs
-46%
RIDEX Steering Angle Sensor
with cable
Article number: 3252S0022
compared to
RRP
£ 109,20
£ 58,70
Price per item
price incl. 20% VAT, excl. delivery costs
-42%
RIDEX Steering Angle Sensor
Article number: 3252S0012
compared to
RRP
£ 169,70
£ 97,78
price incl. 20% VAT, excl. delivery costs
-57%
RIDEX Steering Angle Sensor
Article number: 3252S0018
compared to
RRP
£ 252,60
£ 107,03
Price per item
price incl. 20% VAT, excl. delivery costs
-57%
RIDEX Steering Angle Sensor
Article number: 3252S0015
compared to
RRP
£ 442,30
£ 186,09
price incl. 20% VAT, free delivery
How to test a steering angle sensor
If you need to test your SAS or even a BMW steering angle sensor, you'll need a diagnostic scan tool that is capable of reading SAS data and follow these steps:
- Connect the diagnostic scan tool to the vehicle's OBD-II port.
- Turn on the ignition and select the SAS function on the diagnostic scan tool.
- Calibrate the SAS by following the on-screen instructions. This could involve centering the steering wheel and driving the car in a straight line.
- Once the SAS has been calibrated, observe the data on the diagnostic scan tool while turning the steering wheel. The data should change smoothly and continuously as the wheel is turned.
- If the data is erratic, jumps, or does not change smoothly, the sensor may be faulty and should be replaced.
- If the data appears to be working correctly, check for any fault codes related to the SAS system.
- If there are fault codes present, take a look at the vehicle's service manual for further diagnosis and possible repair.
Testing a steering angle sensor requires specialized equipment and knowledge, so it's best to have it done by a qualified mechanic if you are unsure or suspect that the SAS may be faulty or that the car’s steering rack is worn. While the steering rack and the steering angle sensor are not directly connected, they work together to ensure that the car's steering system is functioning properly and that the driver can maintain control of the vehicle. If either component is malfunctioning, it can cause problems with the car's steering, handling, and safety.
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