CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO P0401)
PERFORM ACTIVE TEST USING INTELLIGENT TESTER (CONTROL THE EGR STEP POSITION)
CHECK FOR DEPOSIT (EXHAUST MANIFOLD CONVERTER TO EGR VALVE)
CHECK FOR DEPOSIT (EGR VALVE TO INTAKE PORT)
READ VALUE USING INTELLIGENT TESTER (MANIFOLD ABSOLUTE PRESSURE SENSOR)