PO401 is the code for insufficent EGR flow.
Most likely the cause is the ports of the egr is plugged up with CARBON! And a simple clean will get it running again.
But sometimes its not that simple.
The EGR valve could be defective and need replacing, it could not be reciting vacuum due to a bad vaccum line, or it could be due to a faulty DPFE sensor for the EGR.
Sunday, March 23rd, 2008 AT 8:53 AM