DTC P0401-00: EGR Flow Insufficient Detected: Notes

DTC P0401:00	EGR flow insufficient detected
DETECTION CONDITION	The PCM monitors the difference in the intake manifold pressures when the EGR is operated and when it is stopped. If the difference is too small, the PCM determines that the EGR flow insufficient. Diagnostic support note This is an intermittent monitor (EGR system). The check engine light illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM. PENDING CODE is available if the PCM detects the above malfunction condition during first drive cycle. FREEZE FRAME DATA (Mode 2)/Snapshot data is available. The DTC is stored in the PCM memory.
FAIL-SAFE FUNCTION	-
POSSIBLE CAUSE	MAP sensor malfunction EGR valve malfunction EGR valve passage malfunction Gasket of EGR valve malfunction EGR valve passage blockage PCM malfunction
SYSTEM WIRING DIAGRAM	-