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1997 Ford Explorer 5.0L Fault Codes P0401 and P0402: Causes and Solutions

Model: 1997 Ford Explorer Fault Code: P0401 Posted: 2009-02-02 04:07

My 1997 Ford Explorer with a 5.0L engine is showing both fault codes P0401 (Insufficient EGR Flow) and P0402 (Excessive EGR Flow). How can the same system produce two conflicting EGR flow readings? What are the most common causes of this dual diagnosis?

Related fault codes

P0401P0402

Comments (2)

Anonymous 2009-02-02 09:11

The DPFE (Differential Pressure Feedback EGR) sensor is likely faulty. A defective DPFE can cause inconsistent voltage readings—sometimes indicating high flow, sometimes low flow. Replacing it with an OEM dealer-grade sensor is recommended for reliable performance and accurate diagnostics.

Anonymous 2009-02-02 17:37

A failing DPFE sensor leads to erratic EGR flow signals. The sensor may intermittently register incorrect voltage levels, resulting in both P0401 and P0402 codes being triggered. Always replace the DPFE with a genuine dealer part to ensure consistent readings and resolve these conflicting fault codes.