What does it mean?
C1101 is a Chassis (ABS, traction control, steering) fault code. It indicates: EPS Battery Voltage High .
Symptoms
- Power steering warning lamp on and assistance reduced or lost completely
- Steering suddenly becomes heavy, often right after start up
- Headlights unusually bright or flickering, other modules logging overvoltage codes
- Battery runs hot, smells or the case swells
- Assist returns after a restart, then drops out again
- Charge or battery warning lamp on at the same time
Likely causes
- Overcharging alternator with a failed voltage regulator
- Poor or corroded ground connection at the steering module raising the measured voltage
- Jump starting, a booster pack or a bench charger left connected at too high a setting
- Wrong battery specification or a battery with an internal fault that cannot absorb charge
- Loose or badly repaired alternator output connection causing voltage spikes
- Damaged wiring where the steering feed runs close to a heavy charging cable
- Internal voltage monitoring fault inside the EPS module
How to fix it
- Measure charging voltage at the battery at idle and at raised engine speed with loads on and off
- Compare the module's reported supply voltage in live data with a meter reading at the battery
- Inspect and clean the battery terminals, the main ground straps and the steering module ground
- Check the alternator output connection and the wiring for heat damage and corrosion
- Test the battery, since a failing cell can let voltage climb
- Replace the voltage regulator or alternator if output stays above specification
- Retest the steering system and clear the code only after charging voltage is stable