Many, many things. Have the ECU scanned with an OBD2 scan tool which will retrieve the fault code or codes. With these codes a qualified technician can find the problem.
Have vehicle scanned to determine the problem - usually a problem in the emission control system
you have a problem with your abs system
where is the vacuum system on a 1994 cadillac deville and how do u vacuum it
Three lines total. Two fuel lines, one feed, one return and one EVAP (Evaporative Emission Control System) line.
I need to see the brake diagram for a 95' cadillac sedan deville
i have a 2000 cadillac seville and stability system is on.
97 deville theft system problem
How to reset the theft system on 1997 Cadillac Seville
Linked is the diagram for a 1976 Cadillac DeVille, 1977 should be roughly the same...
The 2003 Cadillac DeVille typically has two catalytic converters. One is located on each side of the exhaust system, as the vehicle is equipped with a V8 engine. These converters are part of the vehicle’s emissions control system, helping to reduce harmful exhaust emissions.
A 1998 Cadillac Deville does not have a blower relay. The system has a fuse and a controller to feed power to the blower motor.
O2 sensor, and catalytic converter can be ruined. You can also cause internal damage to the engine, depending on what the problem is. Have it repaired.