Check Engine Light Due to Intake Manifold Vacuum Leaks on Cadillac Seville SLS

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.

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Average mileage: 111,600 (59,000–143,000)
11 model years affected: 1994, 1995, 1996, 1997, more1998, 1999, 2000, 2001, 2002, 2003, 2004
18 people reported this problem
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problem details
2003 Cadillac Seville SLS 59,000 mi,
intake boot cracked due to bad front motor mounts
2001 Cadillac Seville SLS 143,000 mi,
Found a hose was not plugged in, plugged it back in. Error code went away in about 10 seconds.
P0101, P0300, P0131, P0171, P0174