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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 33048
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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How do you fix error code P1401 on a 1999 Ford Expedition?

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How do you fix error code P1401 on a 1999 Ford Expedition?



Thank you for asking your question on JustAnswer.

In most case the code 1401 is set due to a bad DPFE sensor and replacing it will likely correct your issue.


Check the Differential Pressure Feedback EGR (DPFE) sensor voltage on a scanner. It should read about 0.4-0.7v if the sensor is aluminum or 0.8-1.2v if the sensor is plastic Key On Engine Off.

If the voltage is abnormally high (above 4.5v typically is the threshold for setting the code), access the sensor and recheck the voltage on the Brown/Light Green (BR/LG) wire. The voltage should match the scanner. If the voltage on the BR/LG wire does match the scanner and is too high, check the Brown/White (BR/WH) wire for 5v reference voltage (vref), and check the Gray/Red (GY/RD) wire for a good ground. If the vref and ground to the sensor are OK but the output voltage is incorrect, suspect a faulty DPFE sensor.

If the voltage at the sensor is low or normal but the scanner shows a high reading, locate and repair the high resistance or open circuit between the Powertrain Control Module (PCM) and DPFE Sensor.

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