Diagnostic Trouble Code
P0401
Insufficient EGR Flow
Technical Description P0401
Insufficient Exhaust Gas Recirculation (EGR) Flow
What Does This Mean P0401?
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 emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR.
EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR.
Possible Causes P0401
1
The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
2
There is a blockage in the EGR (tube), most likely carbon buildup
3
The EGR valve is faulty
4
The EGR valve may not be opening due to a lack of vaccuum
Solutions & Repair Steps P0401
In fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit.
Related EGR codes: P0400, P0402, P0403, P0404, P0405, P0406, P0407, P0408, P0409
Related EGR codes: P0400, P0402, P0403, P0404, P0405, P0406, P0407, P0408, P0409