How to Troubleshoot and Reset Steering Angle Sensor Defects in Your Mercedes

The Mercedes-Benz models are designed with a dazzling array of safety and stability systems and one of the most important components includes the Steering Angle Sensor. In case of a faulty sensor the warning lights can turn off the safety key features leaving you in a vehicle that feels unsafe to drive. Being able to see what the SAS performs, how it fails and how you can restart it or change it would save you a real lot of time and money in repair.

Understanding the Steering Angle Sensor

The Steering Angle Sensor is mounted inside the steering column and is usually located in the clock spring or steering column module. Its main task is to constantly determine the steering wheel position and rate of turn and transmit these values to the Electronic Stability Program (ESP), Anti-lock Braking System (ABS) and other dynamic driving control systems of the vehicle.

As you turn your wheel the SAS informs the car of the amount and speed at which you are turning it. This data is used to determine whether your car is traveling in the direction you desire and to trigger specific braking force or engine torque interventions when it is not. Such systems cannot operate without precise SAS data.

Typical Symptoms of a Defective Steering Angle Sensor

Dashboard warning lights- ESP, ABS or BAS (Brake Assist System) warning lights are the most common. You can either have a yellow triangle with an exclamation point or a car with skid lines turned on in the instrument panel.

Limited stability and traction control - Once the SAS receives corrupted or out-of-range data then the ESP and the TCS implement self-deactivation as a precautionary measure. You will find that there will be lower stability in handling particularly when wet or slippery.

Fluttering steering action - Some drivers have complained of the steering feeling loose, unusually heavy or atypical especially on cars using the Active Body Control (ABC) or Parktronic steering systems which rely on steering input.

Fault codes stored in the ECU - A diagnostic scan will show you certain fault codes related to steering angle sensor circuit faults or ESP fault codes that directly identify the SAS.

Steering not returning to center - In other vehicles the steering controlled by an electronic system can drift or pull as the electronic system does not have a reference point for what is considered straight ahead.

Step-by-Step Troubleshooting

l Diagnostic Scan Have a professional-grade OBD-II scanner with Mercedes STAR Diagnostics or a compatible third-party tool. Provide an inventory of all the stored fault codes on the ABS, ESP and SAS modules. Inspect all of the codes prior to clearing anything.

l Check the Wiring and Connectors. Physical damage acts as an offender. Visually examine the steering column wiring harness to verify that there is no fraying, corrosion or moisture penetration.

l A slack or corroded connector may appear like a faulty sensor. Wipe down clean electrical contacts with electrical contact cleaner and firmly reset the connector.

l Check the Battery Voltage. A weak or failed battery may lead to any type of sensor error in the current Mercedes cars. Inspect to make sure that battery voltage is over 12.4 V when at rest and the alternator is delivering accurate 13.8-14.5 V under load. Check battery problems prior to replacing sensors.

l Check the Clock Spring. The clock spring is the piece of wire connecting the steering column and the steering wheel and it holds electrical continuity by rotating.

l The SAS signals will be disturbed by a broken or worn-out clock spring. When the horn or steering wheel controls fail then the clock spring is likely the source of the problem.

Restarting the Steering Angle Sensor

Through Diagnostic Software - Attach your Mercedes-compatible scanner, select the ESP module or SAS module and choose any one of the following like a Steering Angle Sensor Calibration or SAS Reset.

Manual Reset - In this method the ignition is turned on but the engine is not switched on. Rotate the steering wheel completely to the left lock and then completely to the right lock and back to the center.

Post-Alignment Reset - It is always advisable to reset the SAS after aligning the wheels. Any alteration in suspension geometry will alter the straight-ahead point of reference of the vehicle and will lead the SAS to provide false information.

Conclusion

The Steering Angle Sensor is a small device that has a significant impact on the safety architecture of your Mercedes. Timely diagnosis, thorough inspection of other components around and recalibration following any type of repair will help you get back the driving confidence of your vehicle and the high-tech safety equipment of your vehicle to perform in the manner it was designed.

If you are facing such issues then don't neglect the safety of your vehicle. You can visit us. We have certified Mercedes specialists to provide the expert calibration and precision care your vehicle deserves. Book an appointment with us today to schedule a professional diagnostic and we will ensure your Mercedes remains in peak condition.

We at Tanner Motors located in Phoenix, AZ is a leading shop in the entire area for repairing and servicing European cars. We specialize in Volvo, BMW, Mini Cooper, Mercedes Benz, Lexus and Audi. All our technicians are factory trained.