P004B Fault Code

P004B OBD-II Trouble Code Short Description

Turbocharger/Supercharger Boost Control B Circuit Range/Performance

What does trouble code P004B mean?

The P004B fault code refers to a Turbocharger or Supercharger Boost Control B Circuit Range/Performance issue. This code is commonly found on vehicles equipped with turbochargers or superchargers. It indicates that there may be a problem with the boost control system, specifically in circuit B.

The boost control system is responsible for regulating the amount of air pressure delivered to the engine's intake manifold, which affects the engine's performance and power output. If there is a malfunction in circuit B, it means that the control module is not receiving the expected range of values from the boost control sensor or actuator.

Possible causes of this fault code include a faulty boost control sensor or actuator, loose or damaged wiring/connectors related to the boost control system, a vacuum leak in the intake system, or a problem with the engine's computer.

To diagnose and resolve this issue, it is recommended to perform the following steps:

  1. Inspect the boost control sensor and actuator for any signs of damage or wear. Replace them if necessary.
  2. Check the wiring and connectors related to the boost control system for any loose connections, corrosion, or damage. Repair or replace as needed.
  3. Inspect the intake system for vacuum leaks, which can affect the boost control system. Repair any leaks found.
  4. Clear the fault code using a diagnostic tool and see if it returns. If it does, further diagnosis may be needed to identify the underlying issue.
  5. If the problem persists, it is advisable to seek assistance from a qualified mechanic or dealership for a more in-depth diagnosis and repair.

It is important to address this fault code promptly as it can affect the engine's performance and fuel efficiency. Ignoring the issue may lead to further engine damage or a decrease in overall driving performance.


What are the symptoms of the P004B code?

The P004B fault code indicates a problem with the turbocharger/supercharger boost control B circuit. Some common symptoms associated with this error code on cars may include:

  • Loss of power: The vehicle may experience a noticeable decrease in power and acceleration.
  • Poor engine performance: The engine may run rough, misfire, or hesitate during acceleration.
  • Decreased fuel efficiency: The car may have reduced fuel efficiency due to an improper boost control.
  • Check Engine Light: The check engine light may illuminate on the dashboard, indicating a fault with the boost control system.

Please note that these symptoms may vary depending on the make and model of the vehicle. It is recommended to have the vehicle diagnosed by a professional mechanic to pinpoint the exact cause of the issue.


What causes the P004B code?

The P004B fault code indicates a Turbocharger/Supercharger Boost Control B Circuit Range/Performance issue in a vehicle. This code can have several potential causes, including:

  1. Boost pressure sensor malfunction: A faulty boost pressure sensor can send incorrect signals to the engine control module (ECM), leading to the P004B code.

  2. Boost control solenoid failure: The boost control solenoid regulates the turbocharger or supercharger boost pressure. If it becomes defective, it can cause improper boost control and trigger the P004B code.

  3. Wiring or connector issues: Damaged or loose wiring, as well as faulty connectors, can disrupt the signal between the boost pressure sensor, boost control solenoid, and ECM, resulting in the P004B fault code.

  4. Vacuum leaks: Any leaks in the intake system, such as torn hoses or loose connections, can cause a drop in boost pressure and trigger the P004B code.

  5. Faulty turbocharger/supercharger: A worn-out or malfunctioning turbocharger or supercharger can lead to inconsistent boost pressure readings, resulting in the P004B code.

If you encounter the P004B fault code in your vehicle, it is recommended to consult a professional mechanic for a thorough diagnosis and appropriate repairs.

Possible Solutions

How to fix P004B?

To fix the P004B fault code on cars, you can follow these steps:

  1. Check for any damaged or disconnected vacuum lines or hoses related to the turbocharger/supercharger boost control system. Replace or repair any damaged components.
  2. Inspect the electrical connectors and wiring associated with the boost control solenoid or actuator. Clean or replace any corroded connectors and repair any damaged wiring.
  3. Inspect the turbocharger/supercharger boost control solenoid or actuator for any signs of malfunction or improper operation. Replace the solenoid or actuator if necessary.
  4. Check the operation of the wastegate or bypass valve. Clean or replace if it is stuck or not functioning properly.
  5. Clear the fault code using a scan tool or by disconnecting the vehicle's battery for a few minutes.
  6. Test drive the vehicle to verify if the fault code reoccurs. If the code returns, further diagnosis may be needed to identify the underlying issue.

Please note that it is recommended to consult a professional mechanic or refer to the vehicle's service manual for specific instructions and diagnostic procedures for your particular make and model.