2006 Mazda MX-5 Miata BaseFACTORY OEM SERVICE PROCEDURE

DTC P0401: Notes

DETECTION CONDITION AND POSSIBLE CAUSE (DTC P0401)

DTC P0401 EGR flow insufficient detected
DETECTION CONDITION 
  • PCM monitors difference in intake manifold pressures when EGR is operated and when it is stopped. If the difference is too small, PCM determines that EGR flow insufficient.
Diagnostic support note 
  • This is an intermittent monitor (EGR system).
  • The MIL illuminates if the PCM detects 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 the first drive cycle.
  • FREEZE FRAME DATA is available.
  • The DTC is stored in the PCM memory.
POSSIBLE CAUSE 
  • EGR valve malfunction
  • MAP sensor malfunction
  • EGR gasket malfunction
  • PCM malfunction
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