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P0234 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


The DTC (diagnostic trouble code) P0234, is a generic OBD-II trouble code that can be defined as Turbocharger/Supercharger “A” over boost condition code 


The diagnostic trouble code (DTC) P0234 conveys that the engine’s forced induction system is at risk due to high pressure, recognized by the Powertrain Control Module (PCM). There is a vacuum in engine and piston moves in and out to draw the fuel and air. A turbocharger is employed to boost the engine power. This exerts extra pressure on engine and it may cause a dagame. When the PCM detects that the boosted pressure has exceeded the manufacturer’s limit, code P0234 is triggered. This code must be corrected immediately to avoid any damage to the engine and its components.


The following are the possible causes for this DTC code:

  • The wastegate is either jammed close, forcing the turbo to spin at a faster rate than normal condition, resulting in the over-boosted engine, or it is partially open. This is due to the connecting rod, from wastegate actuator to the wastegate on the turbo, is bent
  • A loose pipe connection to the wastegate or boost controller
  • A clog has formed in the supply house, this may cause blockage in boost controller or in wastegate controller
  • The harness for the boost pressure sensor is open or shorted
  • The electrical connection between the boost pressure sensor circuit and the power supply is weak
  • A faulty boost pressure sensor has been identified
  • Turbocharger or supercharger is not working properly
  • The engine has reached highest operating temperature


The symptoms of a P0234 code will vary depending on the cause of the over-boost condition:

  • The check engine light or service engine soon light will illuminate
  • Lack of engine power will be felt
  • Overheating symptoms may be present in the engine
  • Overheating and hard shifting may occur in the gearbox
  • P0234 may have other codes associated with it to help identify the reason. Codes are available for all electrical components used by the engine management computer.
  • Knocking may be heard from the engine as a result of pre-ignition
  • The engine may show signs of ignition misfiring


A P0234 code is not easy to decode. Several causes might generate excessive engine boost. Finding out which one caused the code might be laborious, especially if someone is new to vehicle maintenance.

  • Examine the wastegate actuator rod
  • Inspect the hoses, especially the one from the boost controller to the wastegate actuator. Look for cracks or hoses. Examine the hose ends for clogs
  • Check, how the wastegate controller and vacuum pump is working. If these components are working slowly, check the connecting rod. Note the inches of mercury required to move the rod, or whether it moves at all. Consult a service manual for vacuum requirements
  • Check the turbo’s internal wastage actuator
  • Start the engine and remove the boost controller supply pipe. Find snags and increase pressure. Install and remove the hose on the boost controller’s other side and check the boost pressure

Common mistakes

Here are some easy tips to follow in order to avoid misdiagnosis:

  • The boost pressure sensor hose may have some blockages or kinks. As a result, you must thoroughly examine it
  • Check to ensure that the high-pressure problem is not caused by an erroneous boost pressure sensor input voltage

How serious is this?

The structural integrity of the engine may be compromised if one experiences a high pressure boosted engine scenario for a long time.

What repairs can fix the code?

repair manualsrepair manuals

DTC P0234 code is a general problem code, meaning it may be set in any vehicle. However, no uniform solution exists for all cars.

  • Examine the discharge valve’s actuator rod. As needed, repair or replace
  • Examine the hoses, especially the one connecting the impulse controller to the discharge gate actuator
  • Examine the controller’s power cables as well. Check that they are in excellent shape, that there are no fractures, and that they are not disconnected. Make certain that no lines are covered. Make the required fixes or changes
  • Connects the discharge valve controller to a vacuum pump. Then, slowly pump while keeping an eye on the actuator rod. You should consider the number of inches of mercury required to operate the rod, as well as whether or not the rod moves. Compare these observations to the manufacturer’s specifications for the vacuum required to trigger the discharge valve. If they do not meet those requirements, the actuator must be replaced
  • If the wastegate actuator cannot hold the vacuum or the rod does not move, the actuator must be replaced
  • If there is a vacuum, but the rod cannot be moved the turbo must be removed, and repair the discharge valve

Additional Information About the Code P0234

Depending on the car manufacturer, the definition of code P0234 may change.

related codes

  • P0235 – Relates to “Turbocharger Boost Sensor A Circuit Malfunction”
  • P0236 – Relates to “Turbocharger Boost Sensor A Circuit Range/Performance”
  • P0237 – Relates to “Turbocharger Boost Sensor A Circuit Low”
  • P0238 – Relates to “Turbocharger Boost Sensor A Circuit High”
  • P0239 – Relates to “Turbocharger Boost Sensor B Circuit Malfunction”
  • P0240 – Relates to “Turbocharger Boost Sensor B Circuit Range/Performance”
  • P0241 – Relates to “Turbocharger Boost Sensor B Circuit Low”
  • P0242 – Relates to “Turbocharger Boost Sensor B Circuit High”
  • P0243 – Relates to “Turbocharger Waste-gate Solenoid A Malfunction”
  • P0244 – Relates to “Turbocharger Waste-gate Solenoid A Range/Performance”
  • P0245 – Relates to “Turbocharger Waste-gate Solenoid A Low”
  • P0246 – Relates to “Turbocharger Waste-gate Solenoid A High”
  • P0247 – Relates to “Turbocharger Waste-gate Solenoid B Malfunction”
  • P0248 – Relates to “Turbocharger Waste-gate Solenoid B Range/Performance”
  • P0249 – Relates to “Turbocharger Waste-gate Solenoid B Low”


DTC P0234 code error poses a grim threat to the vehicle. It may cause grave damage to the engine of the vehicle. One must avoid repairing it at home if one does not have tools, prior knowledge and experience. Consult with the expert for accurate diagnosis and repairs.

P0234 Code – What Does It Mean & How To Fix It