A vacuum leak from the PCV grommet vacuum leak can cause the Check Engine Light to illuminate. The molded rubber hose connections may crack and collapse, causing the vehicle to run roughly. A damaged PCV hose will require replacement.
Car Problem Reports
Lincoln Town Car Check Engine Light Due to PCV Grommet Vacuum Leaks
Lincoln Town Car Problem
Average Mileage: 113,650 mi (98,300 mi - 129,000 mi)
Visitor, 2004 Lincoln Town Car, 98,300 mi
Check Engine Light was on and the engine ran very rough, particularly while idling.
Repaired by Replacing the elbow-crankcase ventilation tube (Ford part number YL8Z-6767-AA) $9.
However it took 2.5 shop labor hours to replace the part, which seemed a bit high.
Visitor, 2000 Lincoln Town Car, 129,000 mi
pcv hose leaking. now engine light comes one also. its been hard to find a replacement part for my 2000 town car though.