C0131 on 2013-2020 Buick Encore: ABS Pressure Circuit Fault Causes and Fixes

What's Unique About the 2013-2020 Buick ENCORE

For the first-generation Buick Encore and its direct platform-mate, the Chevrolet Trax, the brake pressure sensor is not sold as a separate part. It is integrated directly into the Brake Pressure Modulator Valve 🎬 Watch: See where the ABS and traction control modules are located. (BPMV). This design means that a failure of this small sensor requires the replacement of the entire, expensive hydraulic modulator assembly. A specific and well-documented issue noted in GM Technical Service Bulletin PIC5704H is that this code can be triggered immediately after a BPMV replacement if a protective shipping cap is not removed from the new part before installation, causing the sensor to read a constant 5 volts.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• ABS warning light is on
• Traction Control or Stability Control (StabiliTrak) warning light is on
• "Service Traction Control" or "Service StabiliTrak" message on the driver information center
• ABS and traction control systems are disabled
• In some related cases, a flashing StabiliTrak light can be accompanied by reduced engine power, though this often points to other related sensor issues.

Most Likely Causes

1. Internal Failure of the Brake Pressure Sensor 🔴 High Probability The sensor is integrated into the BPMV and is a known failure point across the GM Gamma II platform. The sensor itself can fail electronically or develop an internal fault, leading to implausible signal readings.
   How to confirm: A professional scan tool can monitor the brake pressure sensor voltage. If the voltage is stuck (e.g., at 5 volts) or does not change when the brake pedal is pressed, the sensor has failed. This is a definitive sign of failure.
   Typical fix: Replace the entire Brake Pressure Modulator Valve (BPMV) assembly. The new unit must be programmed and calibrated to the vehicle.
   Est. part cost: $300-$700
2. Failure of the Electronic Brake Control Module (EBCM) ⚪ Low Probability The EBCM is the computer that controls the BPMV. While less common than a sensor failure, the module itself can fail, causing it to misinterpret sensor data or lose communication. It can also be damaged if a new BPMV is installed incorrectly with the shipping cap on.
   How to confirm: This is typically a diagnosis of exclusion. If the BPMV is known to be good and wiring is intact, the EBCM is the likely culprit. Requires advanced diagnostics.
   Typical fix: Replace the Electronic Brake Control Module. This often involves programming the new module to the vehicle's VIN.
   Est. part cost: $160-$300

Rare But Worth Checking

• Shipping Material Left on New BPMV: A GM Technical Service Bulletin (PIC5704H) specifically warns that if the BPMV has been recently replaced, this code will set if a protective shipping cap/plug was not removed from the brake pressure sensor port before installation. This blocks the sensor from reading pressure, causes a stuck 5-volt reading, and can damage the new unit.
• Loose EBCM Mounting: In some cases, if the electronic module (EBCM) is not securely torqued to the hydraulic unit (BPMV), it can cause communication issues that trigger a C0131 code.
• Wiring Harness or Connector Issues: Though less common than internal failure, damage, corrosion, or moisture in the wiring harness or connector at the EBCM can cause an intermittent or constant C0131 code. A thorough visual inspection of the connector pins and wiring loom is a valid diagnostic step.

Diagnosis Steps

1. Connect a professional-grade scan tool capable of reading ABS/chassis codes.
2. Read the DTCs from the Electronic Brake Control Module (EBCM). Confirm C0131 is present.
3. Monitor the live data for the 'Brake Pressure Sensor' parameter while pressing and releasing the brake pedal.
4. If the voltage reading is stuck (often at 5V) or does not change (e.g., stays below 0.15V), this points to a failed sensor or an installation error on a new part.
5. If the BPMV was recently replaced, remove and inspect it to ensure all shipping plugs or caps have been removed as per TSB PIC5704H.
6. Inspect the wiring harness and connector at the EBCM/BPMV for any signs of corrosion, damage, or moisture.
7. If the sensor signal is erratic and wiring is confirmed to be good, the BPMV assembly has an internal fault and requires replacement.
8. After replacement, the new module must be installed, the brake system must be bled using the scan tool's automated bleed procedure, and the Brake Pressure Sensor Calibration function must be performed.

Parts You'll Likely Need

• Brake Pressure Modulator Valve (BPMV) Kit (OEM #94559626) — This is the primary cause of code C0131, as the faulty brake pressure sensor is integrated within this assembly and is not serviceable separately.
  Trusted brands: ACDelco, GM Genuine
  OEM price range: $330-$650
  Aftermarket price range: $250-$500

Technical Service Bulletins (TSBs) & Recalls

• PIC5704H: Provides information about DTC C0131 setting after a Brake Pressure Modulator Valve (BPMV) replacement due to shipping materials not being removed. It notes the sensor will read a stuck 5 volts. This bulletin covers 2013-2022 Encore and Trax models.
• PIC5704G: Predecessor to PIC5704H, covering model years up to 2020 with the same diagnostic information.
• PIC5704F / PIC5704C: Earlier versions of the same bulletin, indicating this has been a known issue since at least 2016.

Platform-Specific Known Issues

• A known issue documented in TSB PIC5704H is the setting of code C0131 immediately after a new Brake Pressure Modulator Valve is installed, caused by failure to remove a shipping plug from the new part. This affects the Encore, Trax, and Sonic.

Mechanic-Grade Diagnostic Values

• Brake Pressure Sensor Signal Voltage (KOEO) — expected: Should vary with brake pedal application. Typically low (e.g., <0.2V) with pedal released.. Failure: Stuck at 5 volts (common with shipping cap issue), less than 0.12 volts, or greater than 3.2 volts for more than 1 second.
• Brake Pressure Sensor Supply Voltage (KOEO) — expected: 4.8 - 5.2 volts. Failure: Less than 4.5 volts or greater than 5.3 volts for more than 1 second.
• EBCM Main Ground Circuit Resistance — expected: Less than 5 ohms to a clean chassis ground point.. Failure: High resistance (e.g., infinite ohms) indicates an open ground circuit, which can cause various EBCM faults.

Hidden / Shadow Codes Worth Checking

• C0131 00: A general ABS Pressure Circuit fault. This is the most common variant. (see via GM GDS2 or equivalent professional scan tool.)
• C0131 3A or 4B: Indicates the EBCM has been replaced, but the required 'Brake Pressure Sensor Calibration' procedure has not been performed or has failed. (see via GM GDS2, Tech 2, or equivalent professional scan tool.)
• C0131 5A: Indicates the EBCM has detected an invalid or implausible signal from the pressure sensor (e.g., pressure reading doesn't match other vehicle dynamics). (see via GM GDS2, Tech 2, or equivalent professional scan tool.)

Scan Tool Commands That Help

• GM GDS2 / Tech2: Brake Pressure Sensor Calibration — This procedure MUST be performed after replacing the EBCM or the BPMV assembly. It learns the home value of the new pressure sensor. Failure to perform this calibration will set a C0131 3A or 4B code.
• GM GDS2 / Tech2: Antilock Brake System Automated Bleed — This is a required 🎬 See this walkthrough on how to perform an ABS brake bleed. service function after replacing the BPMV or opening any hydraulic lines. The procedure cycles the ABS solenoids and pump motor to purge trapped air from the hydraulic modulator, which cannot be done with a manual bleed.

Wiring & Ground Locations

• EBCM Main Ground — The primary ground for the EBCM is typically located on the frame rail or inner fender near the BPMV assembly in the engine compartment.. A poor or corroded ground connection can cause a floating voltage reference, leading to incorrect sensor readings and potentially triggering a C0131 code or communication faults with the module.
• EBCM Connector (X1) — The main electrical connector that plugs into the Electronic Brake Control Module, which is bolted to the side of the aluminum BPMV hydraulic block.. This connector contains all the pins for the internal brake pressure sensor (power, ground, signal). Corrosion, moisture, or backed-out pins in this connector can directly cause an open or short in the sensor circuit, triggering C0131.

Real Owner Repair Stories

• Reddit user in r/AskMechanics (Vehicle not specified, but code and components discussed are identical to the Buick Encore/Chevy Trax platform.) — ABS light on with code C0131.
  ❌ Tried (didn't work) The user was considering replacing the master cylinder or checking for bad wiring before replacing the expensive BPMV.
  ✅ What actually fixed it The user was advised by professionals in the thread that the code almost always points to the internal sensor, and the correct fix is to replace the BPMV/EBCM assembly, followed by the automated bleed and calibration procedures. This aligns with GM's diagnostic procedure for this code.

OEM Part Supersession History

• 95911078 → 95189662 — Part revision by manufacturer.
• 95189662 → 94559626 — Part revision by manufacturer. This is the most current number.
  Heads up: Part 94559626 is specified for Buick Encore and Chevrolet Trax models with active brake control.