P0557
UniversalBrake Booster Pressure Sensor Circuit Low Input
High SeverityThis code indicates that the Powertrain Control Module (PCM) has detected a voltage reading from the Brake Booster Pressure Sensor circuit that is lower than the expected range. This typically means there is an issue with the sensor, its wiring, or a related vacuum problem, potentially leading to reduced power brake assist and a harder brake pedal.
⚠️ Before You Begin (Safety First)
Always ensure the vehicle is safely parked with the parking brake engaged before attempting any inspection or repair. Disconnect the battery before working on electrical components. Allow engine and brake components to cool down completely before touching them to avoid burns. Issues with braking systems should be addressed immediately for your safety and the safety of others.
Common Symptoms
- Check Engine Light (CEL) illuminated
- Hard brake pedal
- Reduced power brake assist
- Increased braking effort required
Common Causes
- Faulty Brake Booster Pressure Sensor
- Damaged or corroded wiring to the sensor
- Short circuit to ground in the sensor circuit
- Poor electrical connection at the sensor or PCM
- Vacuum leak affecting brake booster operation (less direct, but can influence sensor readings)
- Faulty Powertrain Control Module (PCM) (rare)
Frequently reported on: Ford F-Series (2009-2014), Chevrolet Silverado (2007-2013), Honda CR-V (2012-2016), Toyota Camry (2007-2011), Dodge Ram (2009-2018)
Diagnostic Steps
- Park the vehicle safely and engage the parking brake. Disconnect the negative battery terminal.
- Visually inspect the wiring harness and electrical connector for the Brake Booster Pressure Sensor for any signs of damage, fraying, corrosion, or a loose connection.
- Locate the Brake Booster Pressure Sensor, typically mounted on or near the brake booster.
- Using a multimeter, test the voltage at the sensor connector according to your vehicle's service manual to ensure proper power and ground are present.
- Check for vacuum leaks around the brake booster and the vacuum hose connected to it, as a leak can affect pressure readings.
- If wiring and vacuum are confirmed good, test the resistance or voltage output of the Brake Booster Pressure Sensor itself. If it's out of specification, replace it.
- Reconnect the battery, clear the P0557 code with an OBD-II scanner, and perform a test drive to confirm the repair and ensure the code does not return.
👨🔧 When to Call a Professional
If you lack experience with electrical diagnostics or if replacing the Brake Booster Pressure Sensor and checking wiring does not resolve the issue, seek professional help immediately. Braking system integrity is critical for safe vehicle operation.
Commonly Asked Questions
Can I drive my car with a P0557 code?
It is not recommended to drive your vehicle with a P0557 code for an extended period, as it indicates a potential issue with your braking system's power assist, which can compromise safety.
What is the most common cause of P0557?
The most common causes for a P0557 code are a faulty Brake Booster Pressure Sensor or issues with its wiring, such as a short to ground or corrosion in the connector.
How much does it cost to fix P0557?
The cost to fix P0557 can range from approximately $50 to $200 for the sensor part itself. If you opt for professional repair, labor costs could add another $100 to $300, depending on the shop and location.
Does P0557 affect ABS or traction control?
While P0557 is not directly an ABS or traction control code, any issue affecting the brake booster's performance can indirectly impact the overall braking system's effectiveness, which the ABS and traction control systems rely on for proper operation.
Can a vacuum leak cause P0557?
Yes, a significant vacuum leak in the brake booster system can lead to incorrect pressure readings by the sensor, potentially triggering a P0557 code if the reported pressure is outside expected low thresholds.