P401 Code Fixed 4.2L Engine
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P401 Code Fixed 4.2L Engine
After reading several threads and doing some diagnostics;
1. Tested the resistance and supply voltage on the EGR regulator. OK
2. Applied vacuum to the EGR valve to check for holding vaccum and then applied vaccum while running and seeing RPM drop. EGR valve OK
3. Checked for vacuum leaks. None found
4. Backprobed the DPFE sensor was getting~5V at cold startup and ~5V at normal operating temperature. The manual says that there should be a delta in voltage between cold startup and normal temperature, so figured I would try the DPFE sensor.
After replacing sensor and few hundred miles, code has not returned. And engine runs better. Found ford dealer on auction site for $65 shipped, local dealer wanted $120, for the same part, go figure.
Just thought I would share my experience with the P401 code
1. Tested the resistance and supply voltage on the EGR regulator. OK
2. Applied vacuum to the EGR valve to check for holding vaccum and then applied vaccum while running and seeing RPM drop. EGR valve OK
3. Checked for vacuum leaks. None found
4. Backprobed the DPFE sensor was getting~5V at cold startup and ~5V at normal operating temperature. The manual says that there should be a delta in voltage between cold startup and normal temperature, so figured I would try the DPFE sensor.
After replacing sensor and few hundred miles, code has not returned. And engine runs better. Found ford dealer on auction site for $65 shipped, local dealer wanted $120, for the same part, go figure.
Just thought I would share my experience with the P401 code
