On the 2001 Ford Explorer, the P1408 is pointing to a fault in the EGR System. A very common fail item associated with this code is a faulty D.P.F.E (DIFFERENTIAL PRESSURE FEEDBACK EGR) Sensor. Back in the day, there was actually a Recall for this sensor. Ford acknowledged this sensor was defective, so they re-designed and updated it. Carefully inspect the 2 lines at the bottom of the DPFE, looking for any cracks, holes or loose/missing connections. Inspect the electrical connector and wire harness for any loose, broken or damaged wires. If the visual inspection checks ok, replacing the DPFE Sensor should solve the problem.
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