Question about 1998 Ford Expedition
The error code P0401 indicates that the "EGR insufficient flow Detected". I have replace the EGR value,DPFE and the EVR. I reset the error and it runs for 12 miles or so before the light returns?
I would check the front o2 sensors because usually the EGR flow is detected by:
The detect operation of the system, the solenoid is disabled and the o2 compensation control is monitored. If the EGR system is operating properly, turning it off shifts the air/fuel ratio in the lean direction. o2 sensor data should indicate an increase in oxygen in the exhaust gases and cause the short term control to shift rich. The amount of the shift indirectly monitors the operation of the system.
Posted on Oct 13, 2008
Try to clean out the tubes, it is very common for the tubes to get clogged up with carbon, also check for any breaks in the vacuum lines
Posted on Oct 13, 2008
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Insufficient EGR Flow
What does that mean?
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.
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You may notice drivability problems such as pinging (a.k.a. pre-ignition knock) when the engine is under load or the vehicle is at higher speeds. There may also be other symptoms.
A code P0401 most likely means one or more of the following has happened:
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.
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