Technical Description
Inadequate Exhaust Gas Recirculation (EGR) Flow
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles. Although generic, the specific repair steps may vary depending on make/model.
EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emissions system and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. The EGR system generally consists of three parts: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These components work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code indicates that OBD detected an insufficient amount of EGR.
Symptoms
Causes
A code P0401 most likely indicates one or more of the following:
Possible Solutions
When addressing this code, it is common for people to simply replace the EGR valve, only to have the OBD code return. However, the EGR valve is not always the cause.
Related EGR codes: P0400, P0402, P0403, P0404, P0405, P0406, P0407, P0408, P0409
