Common electric power steering failures and their diagnosis

Electric Power Steering (EPS) is a modern automotive technology that has become standard in any passenger car. EPS provides numerous advantages, including fuel efficiency, enhanced safety features, and support for autopilot and automatic parking. Problems with the electric power steering can make the car dangerous, necessitating prompt repairs. Faults in the system can range from simple to complex, with some requiring the replacement of the steering rack. However, experienced professionals can often successfully repair EPS.

How to Diagnose EPS Failures?

Let's explore the common problems with the power steering booster and how to diagnose them.

1. Sensor Malfunction.

    Symptoms: 
    • Uneven response to steering wheel turns.
    • Lack of assistance in specific steering directions.
    • Rack movement without driver input during engine startup.

Diagnosis: Use a diagnostic scanner to read error codes indicating sensor issues. The torque sensor on the dismantled rack can be checked using an oscilloscope after activating the rack with an MS561 tester.

2. Wiring Issues.

     Symptoms: 
     • Temporary EPS malfunctions.
     • Periodic system disconnections.

Diagnosis: Inspect electrical connections, use a multimeter and wiring tester to identify issues like short circuits or breaks. Test the electric power steering on the vehicle using an MS561 tester to rule out amplifier problems.

3. Software Problems.

     Symptoms:
     • Sudden, unexplained power steering disengagement.

Diagnosis:Examine the control unit board for visible defects like water damage, cracked solder joints, or burnt components. If the board is defect-free, a software glitch is possible. Confirm by reprogramming the control unit using an MS561 tester and a diagnostic scanner.

4. Control Unit Problems:

     Symptoms:
     • Lack of response to steering input.
     • Often follows impact or water exposure during heavy rainfall.

Diagnosis:Connect a diagnostic scanner to the vehicle to read error codes. Use an MS561 tester to view data from the control unit.

5. Mechanical Failures:

    Symptoms:
    • Noise over bumps, vibrations, grinding, or crunching during turns.

Diagnosis:Visually inspect the steering mechanism, checking for play and disassemble for an internal examination.
In the online course "EPS Unit Diagnosis and Repair" you can learn the ins and outs of diagnosing EPS faults and how to fix problems with the electric power steering. In this course, we show you how you can quickly and easily find an EPS fault using the MS561 tester.