1991 Cadillac DeVille Problems

An updated PROM (Programmable Read Only Memory) chip may be available for the powertrain control module (PCM).

The spark plugs should be replaced every 30,000 miles and the spark plug boots should be checked for hot spots and cracks.

The powertrain control module (PCM) can fail causing stalling, and various engine and transmission drivability concerns.

You may be able to prevent transmission problems by servicing the transmission and inspecting the fluid every 30,000 miles.

The EGR control solenoid or EGR valve may fail causing the Check Engine Light to illuminate.

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.

Brake fluid can become dirty and may cause problems in the brake system; it should be flushed every 60,000 miles.

Fuel injectors can short-circuit electrically causing a rougher than normal idle and reduced performance.

The air conditioning compressor may become noisy or develop a refrigeration leak, requiring replacement.

The fuel pump may fail causing the engine to stall and not restart.

Excessive carbon build up in the engine combustion chambers may be the cause of a smog check failure due to excess NOx emissions.

The alternator may fail causing the battery to go dead, or an abnormal noise may develop.

The parking brake may not release automatically due to a failed vacuum switch or actuator.

Failure of the catalytic converter can result in illumination of the Check Engine Light.