DTC P0401: EGR System (Insufficient Flow): Notes

If the scan tool indicates DTC P0420, an insufficient flow in the Exhaust Gas Recirculation (EGR) system may exist. See Figure .

Deterioration (clogging, leakage, etc.) in the EGR line or EGR valve is detected by means of the changes in manifold absolute pressure before and after the operation of the EGR valve. If deterioration has been detected during two consecutive driving cycles, the MIL will come on and DTC P0401 will be stored.