The EGR monitor checks the DPF EGR sensor signal to the PCM for low voltage. The test fails when the average voltage to the PCM drops to a voltage less than the minimum calibrated value.
There is a factory service bulletin for the 2001 Ford F-150:
2002 Ford F-150 Factory Service Bulletin OBDII Code P1400 Code
Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
The cost to diagnose the P1400 2002 Ford F150 code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.
Differential Pressure Feedback Electronic (DPFE) circuit low voltage detected
Need more information on how to fix the P1400 2002 Ford F150 code? Get Access to Factory Service Manuals
Get the P1400 2002 Ford F150 code diagnosed by a professional: Find a repair shop in your area