The boost sensor measures the pressure inside the intake manifold. Pressure in the intake manifold is affected by turbocharger output, engine speed, accelerator pedal input, air temperature, and barometric pressure (BARO). A diaphragm within the boost sensor is displaced by the pressure changes that occur from the varying load and operating conditions of the engine. The sensor translates this action into electrical resistance. The boost sensor wiring includes 3 circuits. The engine control module (ECM) supplies a regulated 5 volts to the sensor on a 5-volt reference circuit. The ECM supplies a ground on a low reference circuit. The boost sensor provides a signal voltage to the ECM, relative to pressure, on the boost sensor signal circuit. The ECM converts the signal voltage input to a pressure value. Under normal operation, the lowest pressure that can exist in the intake manifold is equal to the BARO. This occurs when the vehicle is operated at idle or when the ignition is ON while the engine is OFF. The highest manifold pressures occur when the turbocharger output is high. Manifold pressure can range from 58 kPa (8 psi) when pressures are low to more than 240 kPa (34 psi) when pressures are high, depending on the BARO. The boost sensor has a range of 33-255 kPa (4-36 psi). The ECM diagnoses the boost sensor by a calculated predicted value at a predetermined engine load and speed. The ECM then compares the predicted value to the sensor actual input.

The ECM detects excessive high boost pressure for longer than 3 seconds.

DTC P0234 is a Type A DTC.

DTC P0234 is a Type A DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

1. If any other DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further information.
2. Engine running, observe the scan tool MAP and BARO parameters. The reading should be within 1-10 kPa of each other.

1. Engine running, command the TC Vane Pos. Ctrl. Solenoid ON.
2. Perform a snapshot of the engine TC data list while slowly increasing the engine speed to 1,700 RPM, and then back to idle. Refer to Scan Tool Snapshot Procedure .
3. Plot the snapshot and verify that the MAP sensor parameter increases smoothly as the engine speed is increased, and decreases smoothly as the engine speed is returned to idle.

⇒	If the MAP parameter does not change smoothly or does not follow engine speed, inspect the turbocharger for debris, damage, or sticking vanes.

4. If the turbocharger tests normal, replace the manifold absolute pressure (MAP) sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.