Which parts fail
Components named in complaints (engine, cooling system, oil leaks, timing chain, exhaust).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2006 Cadillac STS owners, lightly cleaned up (personal details are redacted by NHTSA).
Tl* the contact owns 2006 Cadillac STS. The contact stated that while driving 60 MPH, the vehicle stalled without warning causing another vehicle to crash into the contact's vehicle. The vehicle rolled over several times ejecting both the contact and front passenger from the vehicle. The driver and front passenger sustained neck, back and brain injuries that required medical attention. A police report was filed. The vehicle was destroyed. The manufacturer was made aware of the failure. The failure mileage was 70,000.
Tl* the contact owned a 2006 Cadillac STS. While driving 45 MPH, the engine stalled without warning and the vehicle crashed into a tree. The failure recurred numerous times prior to the crash. The contact and the two rear passengers sustained injuries that required medical attention. A police report was filed. The vehicle was destroyed and towed to an unknown location. The manufacturer was made aware of the failure. The approximate failure mileage was 60,000. The VIN was unavailable.
I was traveling through the countryside on my way home from work. My car suddenly stalled, I lost control of the vehicle and slammed into an on coming car in the other lane. This caused permanent traumatic brain injury as our airbags never deployed causing us to slam our heads off windshield and side door window.
This problem started over a year ago and I have had it to the dealer twice and they can no find the problem because there are no codes in the car. While driving the car it shuts down and you lose everthing lights, turn singles, hazards,the dash goes totaly out and the engine stops the best you can do it to pull it over to the side of the road and hope you don't get hit. I have had this happen it town driving and on the highway so it has nothing to do with speed. I have loaned my car to other people and it has happened to them so it is not the driver. I will happen and you pull over put the car in park and it starts right up and you can continue driving and it May happen a mile up the road or it May not happen for a week or a month later and still no codes.
Tl* the contact owns a 2006 Cadillac STS. The contact stated that the vehicle experienced an abnormal noise from the engine compartment. The vehicle was taken to an independent mechanic where it was diagnosed that the timing chain was defective and needed to be replaced. The vehicle was repaired. The vehicle also experienced a loss of power. The vehicle was able to be restarted after being shifted into neutral. The vehicle was taken to the dealer where it was diagnosed that the auto start was defective and needed to be replaced. The vehicle was repaired; however, the failure recurred. The manufacturer was notified of the failure. The failure mileage was approximately 60,000.
Stopped the vehicle, placed into park position, shut off car and engaged emergency brake. Removed seat belt, driver and passenger opened doors to exit. Engine at that time went into a very high RPM making a horrible loud whining noise and auto accelerated in reverse with car in park and emergency brake on. Tried to stop the vehicle but brake pedal went to floor. No control of the vehicle and rode the vehicle as it reversed on its own, onto street, through the intersection ,colliding with a parked car and coming to rest with the rear of the car against a building. Speed unknown, no airbags deployed, small injuries.
Tl* the contact owns a 2006 Cadillac STS. While driving various speeds, the vehicle hesitated and sputtered. The vehicle was taken to an independent mechanic who diagnosed that the catalytic converter was faulty and needed to be replaced. While the vehicle was being serviced, the mechanic discovered that the rear tow differential was faulty. The vehicle was not repaired. Woodworth Cadillac (339 n. Main street, andover, ma) and the manufacturer were notified of the failures. The failure mileage was 100,000.
Tl* the contact owns a 2006 Cadillac STS. The contact stated that while driving at approximately 55 MPH, a strong burning odor emitted inside of the vehicle. In addition, drops of oil were visible on the ground. The vehicle was taken to the dealer where it was diagnosed that the front passenger's side axle seal fractured. The vehicle was not repaired. The manufacturer was notified of the failure. The approximate failure mileage was 120,000. .....updated 03/15/16 updated 03/17/16.
Tl* the contact owns a 2006 Cadillac STS. The check engine light remained illuminated. The vehicle was taken to an independent mechanic where it was diagnosed that the engine had eight misfires and the icm needed to be replaced. The vehicle was repaired; however, the failure recurred. The manufacturer was notified of the failure. The approximate failure mileage was 96,000.
Tl* the contact owns a 2006 Cadillac STS. While driving at 60 MPH, the check engine warning indicator illuminated. The vehicle was taken to a dealer where it was diagnosed that the timing chain needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The approximate failure mileage was 76,663.
Engine complaints in other STS years
Frequently asked questions
How common are engine problems on the 2006 Cadillac STS?
NHTSA has 28 complaints about the engine & cooling of the 2006 Cadillac STS, 20% of the model year's 139 complaints. The component named most often is cooling system (1 mentions).
Is there a recall for 2006 Cadillac STS engine problems?
No. NHTSA lists no engine & cooling recall for the 2006 Cadillac STS, though it has 4 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2006 Cadillac STS engine problems start?
Half of the complaints with a recorded mileage happened before about 78,000 miles.
Is it dangerous?
Owners linked 4 crashes, 3 fires and 7 injuries to engine & cooling problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.