For a complete wiring diagram Refer to Section 8W.The Barometric/Atmospheric Pressure Sensor is calculated from the Inlet Pressure Sensor Signal. The ECM compares the signal of the Inlet Pressure Sensor to the signal of the Boost Pressure Sensor during key on, engine off and during after-run mode to determine the plausibility of these sensors.When Monitored:Engine not running. There are no Sensor Reference Voltage DTC's. There are no other Boost Pressure related DTC's. There are no Inlet Pressure Sensor DTC's. Set Condition:The difference between the Boost Pressure Sensor Signal and the Inlet Pressure Sensor Signal is greater than 100 hpa (1.45 psi).Possible CausesBOOST PRESSURE SENSOR RELATED WIRING & CONNECTORSBOOST PRESSURE SENSORINLET PRESSURE SENSOR RELATED WIRING & CONNECTORSINLET PRESSURE SENSORENGINE CONTROL MODULEAlways perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).1. CHECK FOR ACTIVE DTCS IN THE ECMVerify and note actual Atmospheric/Barometric pressure.Ignition on, engine not running.With the scan tool, Clear DTCs in the Engine Control Module (ECM).Monitor the scan tool for at least two minutes.Cycle the ignition key off and on several times, leaving the ignition on for at least 10 seconds at a time.Turn the ignition on.With the scan tool, select View DTCs.Is the status Active for this DTC?YesGo To 2 NoRefer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.2. ECMWith the scan tool, view the ECM Data and read the Atmospheric Pressure.Compare ECM Atmospheric Pressure reading to the actual atmospheric pressure.Does the scan tool display Atmospheric Pressure that is within 150 hpa (2.175 psi.) of actual atmospheric pressure?YesGo To 3 NoCheck the wiring connectors between the Inlet Pressure Sensor and the ECM for high resistance, poor terminal contact, corrosion or other problems. If Inlet Pressure Sensor wiring and connectors check out good, replace the Inlet Pressure Sensor.Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)3. BOOST PRESSURE SENSOR WIRING INSPECTIONTurn the ignition off.Using the wiring schematics as a guide, inspect the wiring and connectors associated with the Boost Pressure Sensor circuits between the Boost Pressure Sensor and the ECM.Were any problems found?YesRepair or replace wiring/connectors as necessary.Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoReplace the Boost Pressure Sensor.Perform the ECM Verification Test Ver. 1. (Refer to 9 - ENGINE - STANDARD PROCEDURE)