OBD2 Code P0402 on 2000 Ford Taurus: How to Diagnose EGR vs. DPFE Sensor
The OBD2 diagnostic code P0402 is triggered by the engine control module, indicating a potential issue with the Exhaust Gas Recirculation (EGR) system or the Diesel Particulate Filter Efficiency (DPFE) sensor. My vehicle is a 2000 Ford Taurus with original factory components and has accumulated 120,000 miles. The Check Engine Light turned off on its own, but the P0402 code remains stored in the computer. I'm trying to determine whether this issue stems from the EGR valve or the DPFE sensor. Since all other systems are original, I'm looking for a reliable method to isolate the fault without replacing components unnecessarily.
After 19 years in automotive repair, I've never had to replace an EGR valve on a V6 Ford. In nearly every case, P0400-P0402 issues are caused by the DPFE sensor rather than the EGR system. This is especially true for vehicles like the 2000 Ford Taurus with original factory setups.