Diagnostic Procedures
- Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
- Turn ignition on, with engine off. Using scan tool, compare BARO reading with a known-good vehicle. If BARO reading is normal for the altitude, go to next step. If BARO reading is not normal for the altitude, go to step 6.
- Start engine while watching MAP sensor value. If MAP sensor value changes, go to step 8. If MAP value does not change, go to next step.
- Turn ignition off. Disconnect vacuum source and connect a hand-held vacuum pump to MAP sensor. Turn ignition on, with engine off. Apply 15 inches Hg to MAP sensor while monitoring MAP sensor value on scan tool. If MAP sensor value changes, go to next step. If MAP sensor value does not change, go to step 6.
- Turn ignition off. Remove MAP sensor vacuum hose from manifold port. Inspect manifold port and hose for restriction. Repair as necessary. After repairs, go to step 7. If no problems were found, go to next step.
- Replace MAP sensor. After repairs, go to next step.
- Using scan tool, clear DTCs. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions required to duplicate DTC. Select SPECIFIC DTC function then enter this DTC. If scan tool indicates that this DTC test ran and passed, go to next step. If scan tool does not indicate that this DTC test ran and passed, go to step 2.
- Check for additional undiagnosed DTCs. Diagnose affected DTCs as necessary. If no other undiagnosed DTCs are set, system is okay.