Technical Definition:

Turbocharger / Supercharger Overboost Condition

Technical Description:

This diagnostic trouble code (DTC) is a generic powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996-newer), although specific repair steps may be slightly different depending on the model.

Trouble code P0234 indicates the powertrain control module (PCM) senses a dangerously high boost pressure from the engine’s forced induction system. Levels of boost in excess of recommended levels can compromise the structural integrity of the engine.

Possible Causes:

• In lieu of further trouble codes associated with the overboost condition it would be safe to say the problem is mechanical. The operation of the wastegate is the most probable.
• The wastegate is either stuck closed causing the turbo to spin higher than normal, thus causing the overboost.
• The rod from the wastegate actuator to the wastegate on the turbo is bent.
• A hose came off the wastegate or boost controller.
• A supply house to the boost controller or from the controller to the wastegate is clogged.
• Dodge trucks with a Cummins diesel have a peculiar problem. They run fine but the check engine light comes on and sets code P0234 at an idle, yet the light goes out several minutes later at cruise speeds. The digital boost control gauge is connected into the MAP sensor which has an intermittent fault at idle yet does not set a code. Replacement of the MAP sensor corrects this.

Possible Symptoms:

• The service engine soon or check engine light will illuminate.
• You will experience a loss of power.
• The engine may show signs of overheating.
• The transmission may show signs of overheating and harsh shifting.
• Additional codes associated with the condition set by P0234 may be present to help identify the cause. Codes are available for all electrical components utilized by the engine management computer for the control of boost levels.
• The engine may display signs of pre-ignition in the form of knocking.
• The engine may display ignition misfiring.

Possible Solutions:

OBD-II Trouble Code Type:

Diagnostic Step:

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