Brake Booster Pressure Sensor Circuit Low
The P0557 code indicates that the brake booster pressure sensor is reporting a voltage lower than the expected range. This sensor monitors vacuum or pressure in the brake booster system, which assists braking. A low signal can result from a faulty sensor, wiring issues, or a vacuum leak, potentially reducing brake assist and increasing stopping distance.
1. Most Common Causes
- Faulty brake booster pressure sensor
- Open or shorted sensor wiring or connector
- Vacuum leak in brake booster system
- Failed brake booster
2. Symptoms You Will Notice
- Hard brake pedal requiring more effort
- Increased stopping distance
- Illuminated Check Engine Light
- Possible hissing sound from brake booster area
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to verify the code and check for other related codes.
Step 2: Inspect the brake booster pressure sensor connector and wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor voltage with a multimeter; compare to manufacturer specifications.
Step 4: Check for vacuum leaks in the brake booster hose and intake manifold.
Step 5: If all else is okay, replace the brake booster pressure sensor.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended because reduced brake assist can lead to longer stopping distances and potential brake failure, especially in emergency situations.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on the vehicle and shop rates.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.