P0557: Brake Booster Pressure Sensor Circuit Low

What Does The P0557 Code Mean?

Trouble code P0557 is one of several possible codes associated to the Brake Booster Pressure Sensor Circuit.

This code is an indication that the Powertrain Control Module (PCM) has detected a malfunction that is hindering the operation of the brake booster pressure sensor circuit.

The codes that are commonly associated to brake booster pressure sensor circuit malfunctions are P0555, P0556, P0557, P0558 and P0559. The specific situation determines the code activated by the PCM and the brake warning light will be illuminated or flash when braking.

The purpose of the brake booster pressure sensor circuit is to monitor the amount of pressure (vacuum) applied to the power brake booster. The circuit is controlled by the PCM to adapt various braking situations and adjust the pressure to assist brake pedal operation.

This process is essential for the power brakes to function properly and safely slow down or stop the vehicle with the minimum amount of foot pressure being applied to the brake pedal.

Code P0557 is set by the PCM when the brake booster pressure sensor circuit has low output voltage.

What Are The Symptoms Of The P0557 Code?

Symptoms of a P0557 trouble code may include:

• Check Brake Light flashes when braking
• Check Brake Light stays illuminated
• An illuminated Service Engine Soon Light
• Increased effort required to depress the brake pedal

What Are The Potential Causes Of The P0557 Code?

Causes for this P0557 code may include:

• Defective brake booster pressure sensor
• Worn or damaged vacuum lines
• Corroded or damaged connector
• Damaged or faulty wiring
• Defective brake booster
• Defective PCM

How Serious Is This P0557 Code?

The severity of this code varies based on the specific malfunction and the severity level will progress if not corrected in a timely manner. At some point the safety level of the vehicle could become an issue requiring immediate attention.

How Can You Fix The P0557 Code?

The first step in the troubleshooting process for any malfunction is to research the Technical Service Bulletins for known issues with the specific vehicle.

Locate all of the components associated with the Brake Booster Pressure Sensor Circuit. This will include the brake booster pressure sensor, the brake booster, vacuum lines, wiring, connectors and the PCM on a simplex system.

Once these components are located, a thorough visual inspection should be conducted to check all of the associated wiring and connectors for obvious defects such as scraping, rubbing, bare wires or burn spots. The connectors should also be examined for corrosion build up or damaged pins. Vacuum lines should be inspected for security, weather cracks, leaks and the overall serviceability level.

Advanced Steps

The advanced steps become very vehicle specific and require the appropriate advanced equipment to perform accurately. These procedures require a digital multi meter and the specific technical references for the vehicle. Voltage requirements will very based of the specific year, make and model of the vehicle.

Circuit Checks

Voltage requirements will vary based on the specific vehicle, the Brake Booster Pressure Sensor Circuit configuration and the components incorporated. Tech data should be referenced to obtain the correct voltage range for the Brake Booster Pressure Sensor and the appropriate trouble shooting sequence. The correct voltage input to a sensor with no output voltage is normally an indication of internal failure.

If this process identifies the absence of a power source or ground, continuity testing may be needed to check the condition of the wiring and connectors. Continuity tests are always performed with the power removed from the circuit and the normal readings should be 0 ohms of resistance unless otherwise specified by the technical data. Resistance or no continuity is an indication of faulty wiring or connectors that are shorted or open and must be repaired or replaced.

Recommended Parts

Below are some recommended auto parts to help you address the trouble code affecting your vehicle and get it running smoothly again:

>>> Brake Booster Pressure Sensor
>>> Vacuum Silicone Tubing Hose
>>> Brake Booster
>>> WORKPRO 582-piece Crimp Terminals, Wire Connectors, Heat Shrink Tube, Electrical Repair Kit
>>> ECU
>>> KAIWEETS Digital Multimeter

Note: During the purchasing process, please check carefully whether the part you want to buy fits your car!

Reference Sources

P0557 Brake Booster Pressure Sensor Circuit Low, OBD-Codes.