01 U0123 – Yaw Sensor Communication Fault: Stability Data Error • 02 Crank Angle in Engines: Everything You Need to Know • 03 B0045: Left Front Side Deploy Loop Short to Ground or Volta… • 04 If You Cut a Car in Half, Will the Front Half Still Drive? • 05 How to Choose the Right SUV: A Comprehensive Guide • 06 Turbochargers and Superchargers: Boosting Performance with … • 07 What is the Fastest Twin Piston Engine Aircraft? • 08 5 Things You Should Know About Oxygen Sensors in Cars • 09 The Best Engines That Should Have Been in Sports Cars But W… • 10 Best Toyota Hiace Diesel Engine: 1KD vs 2KD •

DTC codes / C02xx · Brakes, steering and suspension / C0273

C0273Brake Booster Pressure Sensor Circuit Malfunction

C0273 indicates that the antilock brake system (ABS) control module has detected an electrical fault in the brake booster pressure sensor circuit, which monitors the vacuum or hydraulic assist provided by the brake booster. The computer compares the sensor signal against expected values and sets this code when the voltage or pressure reading falls outside the normal range for a specified time.

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

Symptoms you may notice

  • ABS warning light illuminated on the dashboard
  • Traction control or stability control warning light may also be on
  • Reduced brake assist, requiring harder pedal effort
  • A soft or spongy brake pedal feel
  • Often no symptoms besides the warning light

Common causes, most likely first

  1. Faulty brake booster pressure sensor
  2. Damaged or disconnected wiring or connector at the sensor
  3. Corroded or loose ground connection for the sensor circuit
  4. Vacuum leak in the brake booster or supply hose affecting sensor readings
  5. Failed ABS control module (less common)
  6. Contaminated or restricted sensor port due to debris or fluid

How to diagnose and fix it

  1. Inspect the sensor connector and wiring for damage, corrosion, or looseness
  2. Check for vacuum leaks at the booster and hose connections
  3. Measure sensor reference voltage and signal voltage with a digital multimeter
  4. Compare sensor readings with a known-good sensor or scan tool live data
  5. Test the sensor resistance and output across its operating range
  6. Replace the brake booster pressure sensor if faulty
  7. Clear codes and verify the repair with a test drive

What most technicians overlook on C0273

  • A vacuum leak at the booster can mimic a failed sensor because the sensor reads low assist, so always smoke-test the booster before replacing parts.
  • The sensor connector often suffers from corrosion due to its location near the brake fluid reservoir, causing intermittent codes that disappear after wiggling the harness.
  • Some vehicles use a combined booster pressure and pedal travel sensor; a fault in the pedal sensor can set C0273 as a secondary code.
  • After replacing the sensor, a calibration or relearn procedure may be required on certain ABS modules, and skipping it can leave the code stored.
  • A weak battery or charging system can cause voltage drops that trigger C0273, so check battery health before condemning the sensor.

Can I keep driving with C0273?

You can usually drive the vehicle, but brake assist may be reduced, so increase following distance and avoid heavy braking. Have the fault diagnosed promptly, as loss of assist could lengthen stopping distances in an emergency.

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