Guide To P0555 OBD Error Code Solutions

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OBD-II Code Powertrain Control Module (PCM) failure is defined as a 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 Brake Booster Pressure Sensor measures the amount of vacuum inside the brake booster. If the engine computer sees a doubtful signal from the Brake Booster Pressure Sensor, code P0555 will be set.

Diagnostic trouble code P0555 is technically described as Brake Booster Pressure Sensor Circuit. This is a generic powertrain diagnostic trouble code (DTC) and applies to OBD-II vehicles that have a brake booster pressure sensor. It indicates that PCM has detected a fault in the brake booster pressure sensor circuit. 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. If the PCM fails to receive a voltage input signal from the brake booster pressure sensor that is proportionate to the decrease in vehicle speed required, a code will be stored and a malfunction indicator lamp will be illuminated.

What causes this problem with the Brake Booster Pressure Sensor Circuit?

• Inoperative brake booster
• Faulty brake booster pressure sensor
• Damaged Vacuum lines
• Damaged, broken or corroded wiring and connector
• Poor electrical connection
• Faulty PCM

1. Brake Booster - A brake booster is an enhanced master cylinder setup used to reduce the amount of pedal pressure needed for braking. Replace the faulty one to avoid related error codes.
2. Brake Pedal - Brake pedal is the pedal used by the driver of a vehicle to operate the brakes. It should depress easily else repair or replace as required.
3. Brake Wiring and Connector - Inspect the brake wiring and connector carefully and replace the damaged, corroded or broken immediately.
4. Vacuum Lines - A vacuum line or hose, which can also be referred to as a “line” or a “tube,” is a flexible rubber connection that routes manifold vacuum to various components and accessories. Replace the leaked ones immediately.
5. ECM/PCM - The Engine Control Module (ECM) provides the brains for the engine of the vehicle. In addition to controlling the fuel mixture, the ECM also makes sure the timing and emissions control system work properly, as well as a variety of other systems and sensors.

Below are the common symptoms for the code P0555. If you experience below mentioned symptoms please bring your vehicle to a reputable repair facility. Keep in mind; problems don’t get better over time unless rectified.

• Hard Brake Pedal
• Increased effort required to depress brake pedal
• Flashing of check brake light while braking
• Illuminated check engine light

The reason for this code might be on the smaller side of the monetary Richter scale; however, it is always good to have it checked ASAP because of the extensive variety of potential outcomes. To correct this trouble code all the below mentioned things should be checked first and repair or replace as necessary:

• Replace the faulty brake booster pressure sensor.
• Inspect the brake booster carefully and replace if you discover it frayed or inoperative.
• Check out the corresponding wiring and related connector, repair or replace the damaged, broken or corroded one.
• Faulty ECM/PCM should be diagnosed thoroughly and do the necessary repairs.

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To diagnose this code, one should seek assistance from a trained automotive diagnostician but if you want to do it by yourself, please follow the below mentioned steps:

• 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.
• Check all of the associated wiring and connectors for obvious defects such as scraping, rubbing, bare wires or burn spots.
• Vacuum lines should be inspected for security, weather cracks, leaks and the overall serviceability level.
• With the help of digital multimeter and the specific technical references check the voltage requirements of your vehicle.
• Voltage requirements will vary based on the specific vehicle, the Brake Booster Pressure Sensor Circuit configuration and the components incorporated.
• 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.
• Resistance or no continuity is an indication of faulty wiring or connectors that are shorted or open and must be repaired or replaced.

Common Mistakes When Diagnosing the P0555 Code

Mistakes always happens when you don’t follow the proper steps while diagnosing and the common mistake while diagnosing this code is the replacement of brake booster pressure sensor without even diagnosing it carefully wherein the actual cause is not even touched.