P0401

DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient

Circuit Description

The ECM controls the EGR valve opening based on the engine running condition and by controlling the EGR solenoid.

The EGR valve position is detected by the position sensor and relayed to the ECM. When the proper enabling conditions are met the ECM will open the EGR valve while monitoring the mass air flow (MAF) signal. An expected MAF difference should be detected between the closed and open positions. If the ECM detects the MAF difference less than expected this DTC will set. This DTC will only run once per driving cycle within the enabling conditions.

Condition for Running the DTC

^ DTCs P0027 P0079 P0080 P0101 P0102 P0103 P0112 P0113 P0116 P0117 P0118 P0201 - P0204 P0261 P0264 P0267 P0270 P02E2 P02E3 P02E7 P02E8 PO2E P0300 P0301 - P0304 P0335 P0336 P0403 P0404 P0405 P0406 P0500 P0506 P0507 P0602 P0642 P0643 P0652 P0653 P1125 P2002 P2146 - P2151 P1293 P2227 P2228 P2229 P2454 P2455 and P268A are not set.
^ The battery voltage is between 10 to 16 volts.
^ The ignition switch is ON.
^ The engine speed is between 500 to 800 RPM and does not vary more than 30 RPM.
^ The vehicle is stationary.
^ The accelerator pedal is not depressed.
^ The barometric pressure is more than 11 psi (75 kPa).
^ The intake air temperature is more than 19°F (-7°C).
^ The engine coolant temperature is between 140 to 203°F (60 to 95°C).
^ The intake airflow valve position is more than 50%.
^ The turbocharger control is under normal condition.
^ The exhaust brake valve is commanded OFF.
^ The PTO control is not running.

Condition for Setting the DTC

^ The ECM detects that the MAF amount is not within the calculated range during the EGR flow test. This indicates insufficient amount of EGR flow.

Action Taken When the DTC Sets

^ The ECM illuminates the MIL on the second consecutive driving cycle when the diagnostic runs and fails. Refer to DTC Type Definitions for Action Taken When the DTC Sets - Type B.

Condition for Clearing the DTC

^ Refer to DTC Type Definitions for Condition for Clearing the MIL/DTC - Type B.

Diagnostic Aids

^ If an intermittent condition is suspected refer to Intermittent Conditions in this section
^ A sticking or intermittently sticking the EGR valve may set this DTC.
^ Check the EGR solenoid control circuits at the EGR valve and the ECM for correct terminal tension corrosion or water intrusion.
^ Check the ECM J-12 ground for corrosion/water intrusion and tightness. A loose or corroded J-12 ground will add resistance to the EGR solenoid low side control circuit causing a slow EGR valve change which may cause DTC P0401.

Circuit/System Testing DTC P0401