Illumination of the Check Engine Light can be caused by a loose or worn gas cap.
2009 Cadillac CTS Problem Reports
RepairPal Verified 2009 Cadillac CTS Problem Reports
The front and rear light bulbs are prone to premature failure. Our technicians tell us that the front bulbs can be very difficult to replace.
Vehicles with certain V6 engines may illuminate the Check Engine Light one or more of the following codes: P0011, P0014, P0021, P0024, P0341, P0346, P0336, or P0391. Our technicians tell us that some vehicles may require a powertrain control module (PCM) software update to correct this issue. Other vehicles may have excess camshaft end play on one or both cylinder heads which will need to be corrected using special procedures outlined by GM.