On the 2006 Ford Freestar 3.9L engine, The P0401 is pointing to an insufficient flow in the EGR System. This can be due to a leak somewhere in the EGR System, a faulty EGR Control Solenoid, a faulty EGR Pressure Feedback Sensor or a faulty EGR Valve itself. On this vehicle, the EGR Valve, Pressure Feedback Sensor and Solenoid are all one assembly and labeled as an EGR Module. You can find the EGR Module located on the top, front, driver’s side of the engine. Carefully inspect the metal tubes and rubber lines for any cracks, holes or disconnections. Inspect the electrical connector and wire harness for any loose, broken or damaged wires. If the visual inspection checks ok, replacing the EGR Module should solve the problem.
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