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1997 Ford Explorer 5.0 Engine P0406 DTC: EGR Excessive Flow Issue Without DPFE Sensor

Model: 97 Explorer 5.0 Fault Code: P0402 Posted: 2011-03-16 20:02

I own a 1997 Ford Explorer 5.0 with a persistent P0402 diagnostic trouble code indicating excessive EGR flow. I've confirmed the EGR valve is functioning properly—when manually opened, it operates as expected and produces a continuous vacuum signal from the EGR valve solenoid. My truck does not have a DPFE (Differential Pressure Feedback EGR) sensor, which is standard for this model year and engine configuration. After thoroughly inspecting the engine bay and verifying no DPFE exists, I suspect either a faulty EGR valve solenoid or an internal leak in the EGR system. Despite replacing gaskets, vacuum hoses, and performing a full intake plenum disassembly, the P0402 code persists. I currently lack access to professional diagnostics or proper tools for testing the EGR solenoid resistance or flow rate. Any insights into potential causes or troubleshooting steps would be greatly appreciated.

Related fault codes
P0402
Comments (3)
Anonymous 2011-03-31 09:52

My 1997 Ford Explorer 5.0 also lacks a DPFE sensor. The EGR system flows directly through the intake manifold and plenum, not via a riser pipe where a DPFE would normally be located. I've inspected the EGR valve and solenoid, removed and reinstalled the intake plenum with new gaskets and vacuum hoses, and replaced the PCV system—yet the P0402 code remains. Still looking for solutions.

Anonymous 2011-03-31 16:04

Some Ford 5.0L engines from this era feature an EGR position sensor mounted directly on top of the EGR valve. This sensor may be contributing to incorrect flow readings if it's faulty or not properly calibrated.

Anonymous 2011-03-31 17:04

Check for plugged or restricted ports in the intake system—especially around the EGR passage and vacuum lines—that could cause backpressure and trigger false P0402 codes even with a functioning valve.