An intake manifold vacuum leak can develop from a variety of sources, often causing illumination of the Check Engine Light with codes P0171 & P0174 stored. Thorough diagnoses will be necessary to pinpoint the cause in order to make the correct repairs. A "smoke" machine is often used to isolate the cause of difficult to find vacuum leaks.
Check Engine Light Due to Intake Manifold Vacuum Leaks on Cadillac Seville
Average mileage: 76,000 (76,000–76,000)
12 people reported this problem
1998 Cadillac Seville 76,000 mi, Visitor
engine needs service soon