Common problems with the Cadillac STS include turn signal failures, electrical system issues, leaks in the rear axle pinion seal, air bag issues and problems with the check engine light. The Cadillac STS was a midsize luxury sedan manufactured by Cadillac between 1998 and 2012. The greatest number of problems occurred when the STS model was separated from the Cadillac Seville in 2005.
The light bulbs needed to replace failures in the turn signal and daytime running lights are expensive to replace, even though the problem is not one that affects the engines. Electrical problems associated with the STS primarily involved issues revolving around the car's entire electrical system, the battery and the ignition switch. The rear axle pinion seal problem is easily replaced by replacing the damaged seal, but until it's repaired, the issue may result in internal damage to the vehicle. The primary air bag problem seen in the STS was a failure to deploy. The check engine light problems were minor ones, typically caused because of a loose gas cap.
In addition, the National Highway Traffic Safety Administration issued four recalls for the Cadillac STS between 2005 and 2008. These recalls involved the rear suspension in 2005, the vehicle's speed control in 2006, the fuel pump in 2007 and the exterior lighting in 2008.