1999 Cadillac Seville STS Problems

RepairPal has identified the most common problems with the 1999 Cadillac Seville STS as reported by actual vehicle owners. We'll tell you what the problem is and what it'll take to fix it.

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Known Problems

A Loose or worn gas cap may cause Check Engine Light to illuminate.

Overheating of the engine may cause the cylinder head to expand, severely straining the head bolts and damaging the threads in the engine block. This commonly results in a blown head gasket. Our technicians tell us the engine block threads must be repaired before the cylinder head is reinstalled.

The water pump and/or the plastic side tanks on the radiator may leak causing a loss of coolant. The engine may overheat due to coolant loss. Continued coolant loss after external leaks have been repaired could indicate a blown head gasket.

The trunk pull down switch may fail causing the trunk lid not to close completely. Our technicians tell us that the failed switch can be replaced without changing the complete pull down motor assembly.

The anti-lock brake system (ABS) control module may fail causing the ABS light to illuminate. Failed modules should be replaced to restore ABS operation.

Problems with anti-theft systems using the raised-chip key can prevent the car from starting. The wires in the steering column to the ignition lock cylinder tend to break. The key and ignition lock cylinder should be replaced to correct this condition.

The fuel pump may fail causing the engine to stall and not restart. Our technicians recommend replacing the fuel filter every 30,000 miles to help prevent undue strain on the fuel pump.

One or more heater & AC (HVAC) temperature and/or air delivery mode door actuator may fail, resulting in improper temperature or air delivery. If this occurs, fault code(s) should be stored in the HVAC control module which should assist in diagnoses.

Vehicles equipped with the 4.6L engine may develop excessive oil consumption. Please be advised that under optimum driving conditions, using one quart of oil every 2000 miles is acceptable. This Cadillac standard applies to vehicles with less that 50,000 miles. Our technicians tell us that if you experience excessive oil consumption it may be caused by built up on the piston rings which restricts movement, preventing them from wiping all the oil from the cylinder walls. Oil left behind is then burned during the combustion process. There is a special ring cleaning procedure which can help this situation. The GM service bulletin number is #02-06-01-009C.

The crankshaft position sensor may fail causing the engine to stall intermittently, the Check Engine Light may or may not illuminate.

The spark plugs should be replaced every 100,000 miles. Our technicians recommend replacing the spark plug wires also at this time.

You may be able to prevent transmission problems by servicing the transmission and inspecting the fluid every 30,000 miles. If the fluid is dark or burned then the transmission system should be completely flushed.

The high-pressure power steering lines are known to leak.

The electronic level ride system may not work properly; this may result in the rear of the vehicle riding too high or too low. Our technicians tell us that a height sensor or exhaust valve failure are common issues with this system. Proper diagnoses will be necessary to confirm the exact fault.

It is common for the fuel level sensor in the fuel tank read the fuel level incorrectly. The sensor must be replaced to correct the condition. Our technicians recommend having the complete fuel pump module replaced on high mileage vehicles.