Electric Power Steering Fault
An electric power steering (EPS) warning means the steering-assistance system has detected a fault. The cause can be the steering motor, the EPS control module, a steering-angle sensor, a torque sensor, wiring or a power-supply issue. 'Steering assistance reduced' or 'unavailable' warnings should be diagnosed properly rather than assuming the steering rack needs replacing.
Common Symptoms
Typical signs of this fault include:
What Could Cause It?
This fault can have several underlying causes — not all of them mean a module has failed:
- EPS motor or control module fault
- Steering-angle sensor fault
- Torque sensor fault
- Wiring or connector faults
- Power-supply or earth faults (EPS draws high current)
- CAN/network communication faults
- Software or calibration issues
- Mechanical steering fault affecting the sensor
About the Electric Power Steering Fault System
Electric power steering uses a motor (on the column or the rack) controlled by an EPS module, which reads a torque sensor (driver input) and a steering-angle sensor to provide the right amount of assistance. The system is networked with ABS/ESC for stability functions, so a steering-angle sensor fault can also trigger ABS and stability warnings.
Is the Control Unit Definitely Faulty?
An EPS module or rack is expensive and often replaced unnecessarily. The torque sensor, steering-angle sensor, wiring and power supply should all be checked first — many 'EPS fault' warnings are caused by a sensor or a wiring/power issue rather than the steering rack itself.
How Is It Diagnosed?
At OBD_PAL, we diagnose the complete system before recommending any replacement. Diagnosis typically includes:
Don't guess — diagnose it properly.
- Diagnostic scan of the EPS and steering systems
- Steering-angle sensor calibration check
- Torque-sensor testing
- EPS motor and module testing
- Power-supply and earth testing (EPS needs strong power)
- Wiring and connector inspection
- CAN/network communication checks
- Software and calibration verification
Wiring & Electrical Diagnosis
EPS draws high current, so its power supply and earth connections are critical — a poor earth or voltage drop can trigger an EPS warning under load. Wiring to the steering-angle and torque sensors is also vulnerable. We test the complete power and sensor circuits before recommending a rack or module replacement.
Coding, Programming & Configuration
If an EPS rack or module is replaced, it typically requires coding, configuration and a steering-angle-sensor calibration. Some modules can be cloned; others need full programming.
Calibration & Adaptation
After EPS or steering work, a steering-angle-sensor calibration is usually required so the ABS/ESC system has an accurate steering reference — otherwise ABS and stability warnings can appear.
Don't Replace Modules Based on Guesswork
A fault code is a starting point, not a diagnosis. Many expensive control units are replaced unnecessarily when the real cause is a sensor, a wire, a power supply or a software issue. At OBD_PAL we diagnose the complete system first — don't guess, diagnose it properly — and only replace a module once it's genuinely confirmed faulty.
Electric Power Steering Fault?.
Don't replace expensive parts based on a fault code. OBD_PAL can diagnose the complete system and find the actual cause — then carry out the correct repair, programming or calibration.
This fault guide applies across all makes. For manufacturer-specific electrical diagnostics and module terminology, select your vehicle brand: