C0140 is a chassis/ABS diagnostic trouble code used on applicable Subaru vehicles. It indicates a problem with the ABS hydraulic pressure sensor circuit. The exact definition, sensor configuration, and diagnostic procedure can vary by Subaru model and model year, so the vehicle-specific service information should be used for final diagnosis.
On applicable Subaru vehicles, C0140 can be associated with the ABS/VDC system and the hydraulic brake pressure sensing circuit. The fault may involve the pressure sensor, wiring, connector, power or reference circuit, or the ABS/VDC control unit.
Fault Code Description
C0140 = ABS Hydraulic Pressure Sensor Circuit Fault.
Code type: Chassis / ABS / VDC Diagnostic Trouble Code.
Likely fault location: Hydraulic brake pressure sensor, sensor wiring, connector, power or reference circuit, ground circuit, or ABS/VDC control unit.
C0140 should not automatically be interpreted as a failed pressure sensor. An electrical connection problem or wiring fault can produce the same diagnostic result.
C0140 is a manufacturer-specific chassis/ABS diagnostic trouble code used on applicable Subaru vehicles
What Does C0140 Mean?
The Subaru ABS/VDC control system monitors hydraulic brake pressure so it can control braking force during ABS, traction-control, and vehicle-dynamics operations. If the pressure signal does not match the expected electrical or operating range, the control module can store C0140.
The actual diagnostic criteria depend on the Subaru model and ABS/VDC system. Therefore, the pressure-sensor signal should be checked with an ABS-capable scan tool and compared with Subaru service specifications.
Symptoms of C0140
- ABS warning light.
- VDC or stability-control warning light.
- Traction-control warning indicator.
- Brake-system warning message on applicable models.
- ABS or VDC functions may be disabled.
- Abnormal brake-pressure data on a scan tool.
- Additional ABS/VDC trouble codes.
- In some cases, normal basic braking may remain available.
Common Causes of C0140
- Faulty hydraulic brake pressure sensor.
- Damaged pressure-sensor wiring.
- Loose or corroded electrical connector.
- Damaged connector terminals.
- Open or short circuit in the pressure-sensor circuit.
- Incorrect sensor power or reference voltage.
- Poor sensor ground.
- Hydraulic control unit problem.
- ABS/VDC control module fault.
- Water or moisture intrusion into the connector.
C0140 Subaru
On applicable Subaru vehicles, C0140 should be diagnosed through the ABS/VDC system rather than with a basic engine-only OBD-II scanner. The exact pressure sensor location and circuit arrangement can differ according to the Subaru model, generation, and brake-control system.
A Subaru-specific diagnostic procedure should verify the pressure-sensor signal, wiring, connector condition, power supply, ground, and ABS/VDC module communication before replacing the hydraulic control unit.
Subaru ABS
The ABS control system uses hydraulic pressure information when regulating brake pressure during ABS operation. A pressure-sensor circuit fault can cause the ABS warning light and disable certain brake-control functions.
Subaru VDC
The VDC system may also use brake-pressure information when controlling vehicle stability. A C0140-related fault can therefore affect stability-control operation on applicable models.
The information above applies to applicable Subaru vehicles. Subaru models do not necessarily use identical pressure sensors, wiring, or ABS/VDC modules, so the exact model year and system must be identified before testing.
How to Fix C0140
1. Scan the ABS/VDC System
Use a professional scan tool capable of communicating with the Subaru ABS/VDC control module. Record C0140 and any additional ABS or VDC codes before clearing them.
2. Check the Brake System
Inspect the brake-fluid level and look for visible hydraulic leaks or other obvious brake-system problems. Any abnormal brake operation should be addressed before electrical diagnosis continues.
3. Inspect the Pressure Sensor Connector
Inspect the pressure-sensor connector for corrosion, moisture, loose terminals, damaged pins, broken locking mechanisms, or poor electrical contact.
4. Check Sensor Wiring
Use the correct Subaru wiring diagram to inspect the complete circuit. Look for open wires, short circuits, damaged insulation, high resistance, or wiring damaged by heat, vibration, or previous repairs.
5. Check Power, Reference and Ground
Test the pressure sensor's power or reference circuit and ground according to the specifications for the exact Subaru model. Do not assume that every Subaru ABS system uses the same voltage or pin configuration.
6. Check Pressure Sensor Live Data
Monitor the hydraulic pressure sensor reading with an ABS-capable scan tool. The reading should respond appropriately when the brake pedal is applied and released.
7. Test the ABS/VDC Control Unit
If the pressure sensor, wiring, connector, power, and ground circuits are confirmed to be correct, follow the Subaru diagnostic procedure for the ABS/VDC hydraulic control unit and control module before considering replacement.
C0140 Diagnostic Signal Flow
↓
Master Cylinder / Hydraulic Pressure
↓
Hydraulic Pressure Sensor
↓
Sensor Signal Circuit
↓
ABS / VDC Control Module
↓
ABS / VDC Brake Control
C0140 OBD Live Data
An ABS-capable scan tool can be used to monitor available hydraulic brake-pressure data, brake-pedal status, vehicle speed, ABS status, and VDC-related parameters.
When the brake pedal is released, the pressure reading should correspond to the expected resting condition. When the pedal is applied, the pressure value should respond appropriately. An abnormal or fixed reading can help identify a sensor or circuit problem.
Live data should be combined with electrical testing because an intermittent connector or wiring problem may not always appear during a stationary scan.
Is C0140 Serious?
C0140 can be serious because it is related to the ABS/VDC brake-control system. The vehicle may retain basic mechanical braking, but ABS, traction-control, or stability-control functions may be unavailable depending on the specific Subaru system.
If the brake pedal feels abnormal, braking performance is reduced, brake fluid is leaking, or multiple brake warning lights are illuminated, the vehicle should be inspected before continued driving.
Can I Drive With C0140?
Limited driving may be possible if normal braking remains unaffected, but C0140 should be diagnosed promptly. Driving with an ABS/VDC fault can mean that important electronic braking and stability functions are unavailable.
Avoid driving if the brake pedal becomes unusually soft or hard, braking performance changes, or a hydraulic leak is present.
C0140 Repair Cost
- ABS/VDC diagnostic scan: approximately $50–$150+.
- Electrical diagnosis or wiring repair: approximately $80–$300+.
- Connector repair: approximately $80–$200+.
- Pressure sensor replacement: approximately $150–$500+ where separately serviceable.
- ABS/VDC hydraulic control unit: approximately $500–$1,500+.
- ABS/VDC module replacement or programming: approximately $500–$1,500+ depending on the vehicle.
These are general estimates only. Actual repair costs depend on the Subaru model, brake-system design, parts availability, programming requirements, and labor rates.
Common Repair Mistakes
- Replacing the ABS/VDC module without testing the pressure circuit.
- Assuming the pressure sensor is automatically defective.
- Ignoring corrosion or moisture in the connector.
- Failing to check the sensor power and ground circuits.
- Using an engine-only OBD-II scanner.
- Ignoring additional ABS/VDC codes.
- Using the wrong wiring diagram for the Subaru model.
- Replacing the hydraulic unit before confirming the electrical circuit.
Related Codes
- C0139 – Brake pressure sensor/circuit-related fault on applicable systems.
- C0140 – ABS hydraulic pressure sensor circuit fault on applicable Subaru systems.
- C0057 – Brake pressure sensor/circuit-related code on applicable applications.
- C0042 – Brake pedal or brake-related circuit fault on applicable systems.
The exact definitions of related chassis codes can vary by vehicle manufacturer and ABS/VDC system. Always verify the code using Subaru-specific service information.
FAQ About C0140
What does C0140 mean on a Subaru?
On applicable Subaru vehicles, C0140 indicates a fault involving the ABS hydraulic brake-pressure sensor circuit. The exact diagnostic criteria depend on the model and ABS/VDC system.
Is C0140 an engine code?
No. C0140 is a chassis/ABS-related diagnostic code, not a conventional engine P-code.
Is C0140 a generic OBD-II code?
C0140 should be treated as a manufacturer-dependent chassis code. Its exact meaning and diagnostic procedure can vary between manufacturers and vehicle systems.
Can a bad pressure sensor cause C0140?
Yes. A faulty hydraulic pressure sensor can cause C0140, but the sensor wiring, connector, power, reference, and ground circuits should be tested before replacing it.
Can wiring cause C0140?
Yes. An open circuit, short circuit, high resistance, corroded connector, or damaged wiring can interrupt the pressure-sensor signal and trigger C0140.
Can C0140 turn on the ABS light?
Yes. Because C0140 is associated with the ABS/VDC system, the ABS warning light and other stability-control indicators may illuminate when the fault is active.
Does C0140 mean the ABS module is bad?
No. The ABS/VDC module is only one possible cause. The pressure sensor, wiring, connector, power, reference, and ground circuits should be verified first.
How do I fix C0140 on a Subaru?
Start by scanning the ABS/VDC system, checking related codes, inspecting the pressure sensor and connector, testing the wiring and electrical circuits, and verifying the pressure-sensor live data. Replace the failed component only after the fault has been confirmed.
Final Takeaway
C0140 is an ABS/VDC-related chassis fault that can indicate a problem with the hydraulic brake pressure sensor circuit on applicable Subaru vehicles. The fault may be caused by the sensor, wiring, connector, power or reference circuit, ground, or ABS/VDC control unit.
The most reliable diagnosis is to use an ABS-capable scan tool, monitor pressure-sensor live data, inspect the electrical circuit, and follow the exact Subaru service procedure for the specific model and model year before replacing the hydraulic or electronic control unit.