Brake Booster Pressure Sensor Circuit Intermittent
The P0559 code indicates an intermittent fault in the brake booster pressure sensor circuit. This sensor monitors vacuum or pressure in the brake booster to assist braking. An intermittent signal can cause the powertrain control module (PCM) to detect erratic readings, potentially leading to reduced brake assist or a stiff brake pedal. Common causes include a faulty sensor, damaged wiring, or poor electrical connections.
1. Most Common Causes
- Faulty brake booster pressure sensor
- Damaged or corroded wiring/connectors
- Intermittent short or open in the circuit
- Poor ground connection
2. Symptoms You Will Notice
- Check Engine Light on
- Hard brake pedal or reduced brake assist
- Intermittent loss of power brakes
- Brake pedal feels spongy or inconsistent
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Inspect the brake booster pressure sensor connector and wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor's voltage and ground supply with a multimeter; compare to manufacturer specs.
Step 4: If wiring is intact, replace the brake booster pressure sensor and clear the code.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. An intermittent brake booster sensor can lead to sudden loss of power brake assist, increasing stopping distance and risk of accident.
How much does it cost to fix?▼
Typically $50-$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.