Mercedes-Benz's electrical power steering system may fail, which triggers the following warnings on the dashboard:
- Steering Malfunction See Operator's Manual
- Power Steering Malfunction - Check user's manual
Also, the red power steering light may come on.
If you get this warning, the steering wheel will be difficult to turn because the electric power steering motor is not assisting.
The problem can range from a blown fuse to a faulty power steering motor.
Steering Malfunction See Operator's Manual
If this message comes up while driving:
- Pullover to a safe location and turn off the ignition.
- Wait at least 5 minutes and restart the car. Keep ignition and lights off during this period.
- In many cases, the error message may reset on its own.
If the message comes up when you start the car, further troubleshooting is required.
Is it safe to drive?
Even though newer Mercedes-Benz cars have electric power steering, they have a mechanical link to the steering rack.
It is safe to drive only if you feel you have enough strength to manually turn the steering wheel.
Without the help of the steering motor, the steering wheel will be tough to turn.
The following problems are known to cause problems on Mercedes-Benz with an electrical power steering system.
Low Battery Voltage
The system can malfunction if the battery is partially discharged or the voltage regulator is not working correctly.
Charge the battery using a smart trickle charger.
There is a 125 A pre-fuse that feeds the power steering motor. This fuse can blow, disabling the electric power steering assist.
If the fuse blows, it is an indication of a problem or a lousy steering motor. The fuse is located in the prefuse box in the engine bay.
The power steering motor can fail, which will make the steering very heavy to turn and also trigger the Steering Malfunction. See Operator's Manual error message on the dashboard.
The steering motor is mounted on the steering rack and is easy to replace.
The software for the electric steering may be the culprit and may need to be updated. You will have to take the car to the dealer to get the module updated.
Call your local dealer to check if there is an update available for your steering system.
Approximately 28,000 model-year 2015 Mercedes-Benz C300 and C400 4Matic sedans manufactured between Jan. 27 and Dec. 1, 2014, were recalled due to an error in the electric power steering control unit software.
Due to this problem, a loss of electric power steering assist could occur, necessitating extra steering effort, particularly at lower speeds, and increasing the crash risk.
Check if there is an open recall for your car by going to the NHTSA website. Enter your VIN to see current recalls that apply to your car.
How to diagnose Mercedes Steering Module
- Connect the scanner to the diagnostic port under the dashboard.
- Turn on the ignition.
- Go to Mercedes > Select Model > Control Units
- Select Chassis then Select ES - Electric Power Steering
- Scroll down to read codes and press enter. Review all the codes. Write them down for future reference.
- If you only have stored codes, go back and select Clear Codes to erase them. If codes are present, fix the underlying problem.