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Home >> Lexus >> 2021 >> RX 450h Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostic Codes) (4 Of 8) >> SFI System >> DTC P0401: Exhaust Gas Recirculation Flow Insufficient Detected [10/2015 - 08/2018] >> Description
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DTC P0401: Exhaust Gas Recirculation Flow Insufficient Detected [10/2015 - 08/2018]: Description

Based on the driving conditions, the ECM assembly regulates the volume of exhaust gas that is recirculated to the engine's combustion chambers and thus lowers the combustion temperature to reduce NOx emissions. The ECM assembly monitors signals such as engine speed, engine coolant temperature, electric load, and vehicle speed. When the EGR permission conditions are fulfilled, the ECM assembly controls the opening of the EGR valve linearly through signals to the EGR step motor.

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P0401 Exhaust Gas Recirculation Flow Insufficient Detected Change in intake manifold pressure is small when the EGR valve opened and closed during fuel cut operation (2 trip detection logic).
  • EGR valve assembly
  • EGR passage
  • EGR cooler assembly
  • Intake system
  • Manifold absolute pressure sensor
  • ECM assembly
Comes on DTC stored