CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO P0401)
PERFORM ACTIVE TEST USING INTELLIGENT TESTER (OPERATE EGR VALVE)
READ VALUE USING INTELLIGENT TESTER (MANIFOLD ABSOLUTE PRESSURE SENSOR)
CHECK FOR DEPOSIT (EXHAUST MANIFOLD CONVERTER TO EGR VALVE ASSEMBLY)
CHECK FOR DEPOSIT (EGR VALVE ASSEMBLY TO INTAKE PORT)
CHECK WHETHER DTC OUTPUT RECURS (DTC P0401)
INSPECT VACUUM HOSE SUB-ASSEMBLY
CHECK HARNESS AND CONNECTOR (ECM - EGR VALVE ASSEMBLY - INTEGRATION RELAY)