C0086moderate severityChassis
Master Cylinder Pressure Sensor Circuit Low
on 2012 Subaru Impreza 2.5L H4 · AWD
What this code means
Low voltage from the master cylinder brake pressure sensor, indicating a circuit fault.
Symptoms
- ABS light on
- Stability control disabled
- Brake assist may not function
- Regenerative braking malfunction on hybrids
Common causes
- Sensor short to ground
- Faulty pressure sensor
- Connector pin damage
- Low battery voltage to sensor
Diagnostic steps
- Test sensor supply voltage
- Check signal wire for shorts to ground
- Inspect sensor connector
- Test sensor output while pressing brake pedal
- Check for related ABS module codes
Repair notes
Replace master cylinder pressure sensor. Verify supply voltage.
🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Bluetooth code reader (~$25)
Veepeak OBDCheck BLE →
Pairs with your phone — reads and clears codes, live data.
Serious DIY (~$100)
BlueDriver Pro →
Enhanced codes (ABS, airbag, TPMS) plus repair reports.
Shop-grade tablet (~$300+)
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
As an Amazon Associate, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
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