01 Unveiling the Mystery of Gaskets: Your Key to Automotive Se… • 02 CAN Bus in Cars: Everything You Need to Know • 03 Drivers Are Left Stunned After Discovering The Real Purpose… • 04 Drivers Are Only Just Discovering Why Their Cars Randomly S… • 05 Mastering Motorcycle Hand Signals for Effective Communicati… • 06 This Is Why Your Car’s Door Locks Keep Flickering • 07 C0040 and C0041: Right Front Wheel Speed Circuit Malfunction • 08 The Heart of Automatic Transmissions: A Closer Look at Torq… • 09 The Future of Transportation: The Top Auto Innovations to W… • 10 Understanding Oxygen Sensors and Their Impact on Your Car •

DTC codes / C05xx · Brakes, steering and suspension / C0520

C0520Brake Pedal Force Sensor Circuit

C0520 indicates that the brake pedal force sensor circuit has a fault, meaning the computer is not receiving a valid signal that corresponds to how hard the driver is pressing the brake pedal. The sensor converts pedal force into a voltage or digital message, and the control module sets this code when the signal is out of range, erratic, or missing entirely.

SystemChassis
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaBrakes, steering and suspension

Symptoms you may notice

  • The antilock brake system (ABS) warning light, traction control light, or brake system warning light illuminates on the dashboard.
  • The brake pedal may feel normal, but the vehicle could exhibit reduced ABS or stability control intervention during hard braking.
  • Some vehicles may enter a fail-safe mode that disables hill-start assist or electronic brake-force distribution.
  • A stored code may be the only sign, with no noticeable change in braking performance during normal driving.
  • In rare cases, the cruise control or adaptive cruise control may become inoperative because it relies on brake pedal force data.
  • The driver may notice a slight delay or inconsistency in brake response under emergency stopping conditions.

Common causes, most likely first

  1. Failed brake pedal force sensor itself, due to internal wear or contamination.
  2. Damaged or corroded wiring harness or connector at the sensor or control module.
  3. Open or short circuit in the sensor signal or ground circuit.
  4. Poor electrical connection caused by water intrusion or road salt exposure.
  5. Faulty brake pedal assembly or misadjusted sensor linkage preventing proper sensor travel.
  6. Control module internal fault, though this is less common than sensor or wiring issues.
  7. Aftermarket accessories or improper previous repairs that disturbed the sensor circuit.

How to diagnose and fix it

  1. Connect a scan tool and retrieve all stored codes, then clear the code and test-drive to see if it returns immediately.
  2. Visually inspect the brake pedal force sensor, its connector, and the wiring harness for damage, corrosion, or loose pins.
  3. Measure the sensor reference voltage and ground at the connector with a digital multimeter, comparing to manufacturer specifications.
  4. Back-probe the sensor signal wire and observe the voltage change as the brake pedal is pressed with varying force.
  5. Check for continuity and resistance on the signal and ground circuits between the sensor and the control module.
  6. If the sensor signal is erratic or out of range, replace the brake pedal force sensor and perform any required calibration or relearn procedure.
  7. After repair, clear codes and verify that the warning light stays off and the sensor data reads correctly during a road test.

What a brake force sensor code really means

  • A brake pedal force sensor is often confused with a brake pedal position switch, but the force sensor measures how hard you press, not just whether the pedal is down.
  • The code can set intermittently due to a chafed wire that only loses contact over bumps or during temperature changes, so a wiggle test of the harness is essential.
  • Some vehicles use the force sensor signal for electronic brake-force distribution and hill-start assist, so a fault may disable those features without affecting base braking.
  • A weak or failing battery or charging system can cause voltage spikes that corrupt sensor signals and set this code, so always check battery health first.
  • Replacing the sensor without checking the connector for water intrusion or corrosion often leads to a repeat failure within weeks.

Can I keep driving with C0520?

The vehicle remains safe to drive under normal conditions because the base hydraulic brakes are unaffected, but you should avoid heavy braking or emergency maneuvers until the fault is repaired. If the ABS or stability control warning light is on, reduce speed and allow extra stopping distance, and have the system diagnosed promptly.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage