2012 Jeep Wrangler JK Factory Service Manual 28 - DTC-Based Diagnostics

P0238-TURBO BOOST PRESSURE SENSOR CIRCUIT HIGH

P0238-TURBO BOOST PRESSURE SENSOR CIRCUIT HIGH

For a complete wiring diagram, refer to the Wiring Information.


Theory of Operation

The Boost Pressure Sensor is combined with the Intake Air Temperature (IAT) Sensor 2. It is used to measure the pressure of the air entering the Turbocharger. The Boost Pressure Sensor operates as a typical three wire sensor. It receives a 5-Volt feed on the (K356) Boost Pressure Sensor 5-Volt Supply circuit and shares the (K656) ground circuit with the Boost Pressure Sensor. The PCM receives a signal from the sensor via the (K37) Boost Pressure Sensor Signal circuit. When this fault code is active the EGR system, Boost Pressure Actuator and DPF regeneration will be disabled.



Possible Causes

(K356) BOOST PRESSURE/INTAKE TEMPERATURE SENSOR 5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
(K37) BOOST PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE
(K656) BOOST PRESSURE/INTAKE AIR TEMPERATURE SENSOR GROUND CIRCUIT OPEN/HIGH RESISTANCE
BOOST PRESSURE/INTAKE AIR TEMPERATURE SENSOR
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


1. DTC IS ACTIVE



NOTE: If any Sensor Reference DTCs are present, perform those diagnostic procedures before continuing with this test.
1. Ignition on, engine not running.
2. With the scan tool, select View DTCs.


Is the status Active for this DTC?

Yes


No


2. CHECK THE (K356) BOOST PRESSURE/INTAKE AIR TEMPERATURE 5-VOLT SUPPLY CIRCUIT
1. Turn the ignition off.
2. Disconnect the Boost Pressure/Intake Air Temperature Sensor harness connector.
3. Turn the ignition on.
4. Measure the voltage of the (K356) Boost Pressure Sensor 5-Volt Supply circuit at the Boost Pressure/Intake Air Temperature Sensor harness connector.


Is the voltage above 5.2 Volts?

Yes


No


3. CHECK THE (K37) BOOST PRESSURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE
1. Measure the voltage of the (K37) Boost Pressure Sensor Signal circuit in the Boost Pressure/Intake Air Temperature Sensor harness connector.


Is the voltage above 1.0 Volt?

Yes


No


4. CHECK THE (K656) BOOST PRESSURE/INTAKE AIR TEMPERATURE SENSOR GROUND CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn the ignition off.
2. Disconnect the PCM C1 harness connector.
3. Measure the resistance of the (K656) Boost Pressure/Intake Air Temperature Sensor Ground circuit between the Boost Pressure/Intake Air Temperature Sensor harness connector and the Powertrain Control Module (PCM) harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


5. CHECK THE BOOST PRESSURE SENSOR
1. Turn the ignition off.
2. Reconnect the Boost Pressure/Intake Air Temperature Sensor harness connector.
3. Reconnect the PCM C1 harness connector.
4. Turn the ignition on.
5. With the scan tool, erase DTCs.
6. Turn the ignition off.
7. Disconnect the Boost Pressure/Intake Air Temperature Sensor harness connector.
8. Connect a jumper wire between the (K656) Boost Pressure/Intake Air Temperature Sensor Ground circuit and the (K37) Boost Pressure Sensor Signal circuit in the Boost Pressure/Intake Air Temperature Sensor harness connector.
9. Turn the ignition on.
10. With the scan tool, select View DTCs.


NOTE: The scan tool should display a P0237-Turbo Boost Pressure Sensor Low DTC as active with the jumper wire in place.


Does the scan tool display the DTC as described above?

Yes


No


6. POWERTRAIN CONTROL MODULE

1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors the Boost Pressure/Intake Air Temperature Sensor and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Perform any Technical Service Bulletins that may apply.


Were any problems found?

Yes


No