C0221moderate severityChassis
EPS Control Module Voltage Low
on 2013 Mazda MX-5 Miata 2.0L I4 · RWD
What this code means
The EPS module supply voltage has dropped below the minimum operating threshold.
Symptoms
- EPS warning light
- Power steering assist reduced
- Assist cuts out during electrical load
- Steering heavy at idle with AC on
Common causes
- Low battery voltage
- Weak alternator
- High resistance in EPS power supply wiring
- Corroded battery terminals
- Undersized wiring for EPS current demand
Diagnostic steps
- Measure battery voltage at rest and running
- Test alternator output under load
- Check voltage at EPS module connector
- Inspect battery terminals and cable ends
- Test EPS power supply fuse and connections
Repair notes
Repair charging system. Clean battery connections. Verify adequate wire gauge to EPS module.
Other Chassis codes on this vehicle
C0021
LF Wheel Speed Sensor Range/Performance
C0022
RF Wheel Speed Sensor Range/Performance
C0023
LR Wheel Speed Sensor Range/Performance
C0024
RR Wheel Speed Sensor Range/Performance
C0025
LF Wheel Speed Sensor Circuit Intermittent
C0026
RF Wheel Speed Sensor Circuit Intermittent
C0027
LR Wheel Speed Sensor Circuit Intermittent
C0028
RR Wheel Speed Sensor Circuit Intermittent
C0035
Left Front Wheel Speed Sensor Circuit
C0036
Left Front Wheel Speed Signal Erratic