Review on Standard Motor Products VS52 Solenoid by Michael Robinson

If the Check Engine Light comes on on your 4.6L Ford/Mercury/Lincoln vehicle and you receive a code PO401 or PO402 (or both). There are several possible causes - and this EGR vacuum solenoid valve is one of them. Codes PO401 and PO402 indicate a problem with the exhaust gas flow through the EGR system and often indicate a "clogged” EGR passage. To test the EGR valve with the engine warm and idling, apply vacuum to the fitting on top of the EGR valve. If the engine coughs, runs rough, or stalls when vacuum is applied, the EGR valve is good and the EGR passages are NOT CLOSED. Either the EGR vacuum solenoid (this part) is defective or the DPFE sensor is defective. The original DPFE sensor has a metal base that has been modified to eliminate blocking issues. The new design is plastic and runs MUCH cooler so replacement should take forever. They can be tested, but I chose to replace both the solenoid and DPFE sensor at the same time just to save time and duplicate effort. Both parts are available at Revain.com for fast shipping and great savings. With new parts installed and fuel pressure adjusted, the Mercury V-8 engine runs like silk and has enough power to get you uphill - no more "checking the engine"! light in my face!