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.
Problems for specific Cadillac DeVille years:
Car problem reports
Problem with your car? See what our experts say or submit your own.
Most reported 1995 Cadillac DeVille problems
Fuel injectors can short-circuit electrically causing a rougher than normal idle and reduced performance.
This powertrain control module (PCM) may develop a fault with its electrical ground location at the front of the engine block near the starter motor.
The alternator may fail causing the battery to go dead, or an abnormal noise may develop. The dash warning light may or may not illuminate. A failed alternator will require replacement.
An updated PROM (Programmable Read Only Memory) chip may be available for the powertrain control module (PCM). Check with your dealer.
A coolant leak may develop from the water pump. The engine may overheat as a result of the coolant loss. A leaking water pump should be replaced.
Excessive carbon build up in the engine combustion chambers may be the cause of a smog check failure due to excess NOx emissions. A "top engine" decoarbonization cleaning procedure will commonly correct this concern.