Circuit DescriptionThe combination turbocharger compressor intake pressure/temperature sensor is used to measure ambient air pressure. The pressure measuring portion of the sensor responds to pressure changes in the atmospheric pressure, which occur based on elevation at which the engine is presently operating. The turbocharger compressor intake pressure sensor has a 5 volt supply circuit, a pressure sensor signal voltage, and a return circuit. The ECM will detect a low signal voltage when the vehicle is operating at high altitudes. The ECM will detect a high signal voltage when the vehicle is operating at sea level altitudes.

Component LocationThe combination turbocharger compressor intake pressure/temperature sensor is located in the OEM intake air plumbing.

Conditions for Running the DiagnosticsThis diagnostic runs continuously when the keyswitch is in the ON position.

Conditions for Setting the Fault CodesThe ECM detects that the turbocharger compressor intake pressure signal voltage is greater than 4.75-VDC for more than 10 seconds.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.A default value for the turbocharger compressor intake pressure reading is used.Diesel exhaust fluid injection into the aftertreatment system is disabled.Active and stationary regeneration of the diesel particulate filter will be disabled.The EGR valve will be closed.Engine torque will be reduced if the engine is operated for an extended period of time with this fault code active.Conditions for Clearing the Fault CodeTo validate the repair, start the engine and let it idle for 1 minute.The fault code status displayed by INSITE? electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.The ECM will turn off the amber CHECK ENGINE lamp after the diagnostic runs and passes.For On-Board Diagnostics (OBD) engines, the ECM will turn off the MIL after three consecutive trips where the diagnostic runs and passes.The ?Reset All Faults? command in INSITE? electronic service tool can be used to clear active and inactive fault codes, as well as extinguish the MIL for OBD engines.

Shop TalkThe turbocharger compressor intake pressure/temperature sensor shares supply and return wires in the engine harness with other sensors. Opens and shorts in the engine harness can cause multiple fault codes to be active. Before troubleshooting Fault Code 221, check for multiple fault codes.

Possible causes of this fault code include:

Open return circuit in the harness, connectors, or sensorSignal circuit shorted to sensor supply or battery voltage.

Possible Cause:1) ECM failure2) Engine Harness