The 1st and only generation of the Cadillac STS debuted for the 2005 model year after it branched from being a high-end option for the Cadillac Seville. While it is known as a luxury sedan, no car is perfect. This post covers the most common Cadillac STS problems for model years 2005 to 2011.
Top 5 Issues with the 1st Gen Cadillac STS (2005 to 2011)
1. EVAP Codes for a Bad Gas Cap
Symptoms of a Bad Gas Cap
- Check engine light for an evaporative emission control system (EVAP) code
- Loose gas cap
- Gas cap doesn’t ratchet
- Gas cap gasket is broken, torn, or missing pieces
Causes of a Bad Gas Cap
The gas cap not ratcheting and securing, and the gas cap gasket breaking are usually the cause for a faulty gas cap triggering the check engine light for an EVAP code on the 2005 to 2011 Cadillac STS.
How to Fix a Bad Gas Cap
Inspect the gas cap for tightness, ratcheting, and breaking, tearing, or missing pieces on the gasket. Replace the gas cap if it is defective.
2. Camshaft Actuator Solenoid Valve Failure
Symptoms of Bad Camshaft Actuator Solenoid Valve
- Check engine light and possibly drivability issues from trouble properly timing the cams
How to Prevent Camshaft Actuator Solenoid Valve Failure
Keep the oil at the proper level and change the oil regularly to prevent the solenoid valves from failing.
3. MAP Sensor Failure
Symptoms of a Bad MAP Sensor
- Check engine for a MAP sensor code
How to Fix MAP Sensor Failure
The MAP sensor is located on the intake manifold on the V6 and V8 engines. To remove it, disconnect the electric connector, remove the bolt, and remove the sensor. Reverse this procedure to reinstall a new one.
4. Passenger Presence Sensor Failure
Symptoms of a Bad Passenger Presence Sensor
- Check air bag light is on with a code for the passenger presence system
Causes of Passenger Presence Sensor Failure
The passenger presence sensor is located in the passenger seat. It senses if there is a passenger on the seat for the air bag system so an airbag can deploy during an accident.
Pro Tip: Do not place any objects on the seat because that can damage the sensor. Only a passenger should be on the seat.
How to Fix the Passenger Presence Sensor
Replace the sensor. It’s an inflated bag with air that is apart of the seat cushion.
5. Steering Wheel Position Sensor Failure
Symptoms of a Faulty Steering Wheel Position Sensor
- Service stability light is on on the dash
- ABS light is on
- Might notice ABS light activating for no reason while driving
Causes of Steering Wheel Position Sensor Problems on the 2005 to 2011 Cadillac STS
The steering wheel position sensor is located at the base of the steering column. It sense the steering wheel’s position and sends a signal to the ABS module for the stability system. Sometimes it can fail on the 1st gen Cadillac STS.
How to Fix Steering Wheel Position Sensor Failure
To replace the steering wheel position sensor, steps include disabling the air bag system, removing the lower dash panels, removing the intermediate shaft, and sliding the sensor out. Reserve these steps to reinstall.
1st Generation Cadillac STS Model Years
- 2005 Cadillac STS
- 2006 Cadillac STS
- 2007 Cadillac STS
- 2008 Cadillac STS
- 2009 Cadillac STS
- 2010 Cadillac STS
- 2011 Cadillac STS