General Motors’ Sigma platform was responsible for shaping the company line-up in the early 2000s. It was this midsize platform that popular models like the Cadillac CTS and SRX were based on. Another model that used this platform was what was considered to be a larger alternative to the CTS — the Cadillac STS.
Despite being a four-door, a rear-wheel-drive sedan like the CTS, the STS was a step-up in many ways. The 2005 Cadillac STS was also more luxurious, especially in terms of its interior. It was also roomier and quieter on the inside. That wasn’t all that made the STS, there were also many other contributing factors which we’ll touch upon a little later. We will also discuss whether it’s reliable and its known issues as we always do in our buyers’ guides.
What Does STS Mean on a Cadillac?
The 2005 Cadillac STS replaced the company’s long-lasting Seville. Interestingly, STS which stands for Seville Touring Sedan was originally a variant of the Seville. Back in 1987, Cadillac offered two variants, the aforementioned STS which was the performance-oriented variant, and an SLS (Seville Luxury Sedan) that as its name suggests prioritized comfort. The Seville part of its name was inspired by the Spanish province of Seville.
STS or Seville Luxury Sedan title is also quite indicative of what the car was all about. It was targeted at buyers looking for domestic luxury. Cadillac’s vivid past also meant that they knew a thing or two about making luxurious vehicles.
Taking a Look At The 2005 Cadillac STS
While we are discussing Cadillac’s past, it’s important to note the company’s Seville used a front-wheel-drive configuration while the 2005 Cadillac STS made use of a rear-wheel-drive one. You could also option the 2005 Cadillac STS with an all-wheel-drive system. Another fact is that the 2005 Cadillac STS was built to take on the BMW 5 Series and the Mercedes-Benz E-Class sedans.
This meant it had to deliver in more ways than one, when it came to its suspension the car could be optioned with a magnetic ride control system that was also found on its predecessor. This is because it was proven tech that buyers were quite fond of. Other offerings based on this platform also used a magnetic ride control system. The 2005 Cadillac STS was also longer than its predecessor, which helped with the room on the inside.
Cars in this segment weren’t only meant to be comfortable on the inside, but also well-equipped. This is why Cadillac offered a heads-up display and a 300-watt Bose sound system with MP3 capability. The car also had a push to start system which was almost unheard of at the time. Dual-zone climate control, a six-CD changer, and heated seats were part of the standard equipment.
The 2005 Cadillac STS was available with two engine options. The first one was the 3.6 V6 High Feature LY7 unit that made 255 hp and 252 lb-ft. The second one, meanwhile, was the 4.6 V8 Northstar LH2 that made more power and torque at 320 hp and 315lb-ft. These engines were also available with other vehicles that used the Sigma platform. With features and technologies like variable valve timing and dual overhead camshafts, they were also properly well-equipped for the time.
2005 Cadillac STS Updates
The 2005 Cadillac STS was on sale for a total of three years until it was benched for a newer model in 2008. In its three years of production, it witnessed some smaller updates.
2006 Cadillac STS
In 2006, the American carmaker introduced the all-wheel-drive system as a stand-alone option for 2006 V6-equipped cars. Cadillac also added a more powerful STS-V to the range. Powering it was a supercharged V8 that made an impressive 469 hp.
2007 Cadillac STS
Not much changed in 2007 aside from the addition of a six-speed automatic transmission on all V8-equipped Cadillac STSs.
Cadillac STS – What Made It Special
Multiple factors made the 2005 Cadillac STS special. To begin with, it was the company’s flagship sedan. The company was also shifting towards a new direction at the time and the 2005 Cadillac STS was making that clear. This was the car where the company showcased its technological prowess which is why it was loaded with the latest and greatest features.
Most notable features included the 320 hp V8 engine, the sophisticated all-wheel-drive, radar-based cruise control, and the optional magnetic ride control system. The car was also designed to take on the midsize luxury sedan space, which meant it had to be well put-together, luxurious and powerful, and it certainly was.
Is The 2005 Cadillacs STS Reliable?
If you look at the ownership reviews of the 2005 Cadillac STS it proves that the car is quite reliable, just like the Cadillac CTS which shares the same platform. You would think that General Motors would have made some blunders when producing a car this technologically advanced for the first time, but that’s not the case. Yes the Cadillac STS has its fair share of known issues and drawbacks, but none of them can be considered to be deal-breakers. Overall, the 2005 Cadillac STS is fairly reliable if you learn how to live with and deal with some of its known issues.
Known Issues
Speaking of its known issues, the 2005 Cadillac STS has a few from small things like the gas cap to major ones like timing chain-related issues with its engine. Here’s the complete breakdown of the most common problems with this vehicle.
Steering Wheel Position Sensor
The steering wheel position sensor sits at the base of the steering column and gathers data about the position of the steering wheel. It takes this data and sends it to the computer handling the stability system. This information is used along with the ABS when necessary. This sensor can go bad which can lead to either a service or ABS light illuminating the dashboard. It’s best to get this addressed quickly as it can cause the ABS to activate without reason.
MAP Sensor
As we mentioned before, the Cadillac STS is quite heavy on tech which means it comes equipped with a bunch of sensors. Another that goes bad is the MAP sensor or the Manifold Absolute Pressure sensor. When this sensor begins failing, you will notice problems with the performance of the car and a check engine light. The car will also have an error code that will specify the problem.
Gas Cap
If your gas cap isn’t sealed properly on the Cadillac STS it can lead to a check engine light along with an evap code. The inefficiency in terms of the seal occurs due to a problem with the gasket. This is a widely reported problem and can only be fixed by replacing which is quite straightforward.
Timing Chain
One of the bigger issues with the 2005 Cadillac STS is where its timing chain stretches. This is a problem that’s seen only on the V6 models and not the V8 cars. There are a couple of reasons why this problem occurs, and it has to be thoroughly inspected before purchase. Make sure there’s nothing wrong with the timing chain of the STS as one that’s failing can cause major problems.
Ignition Coil
The 2005 Cadillac STS also uses coil-on-plug ignition coils and these coils don’t have very long service intervals. It is reported that the STS can require a new set of ignition coils sooner than expected, but it still depends on the usage pattern. We highly recommend replacing the entire set of ignition coils if the STS has just entered your garage. The Bosch 0221604112 ignition coils are among the best out there.
Camshaft Actuator Solenoid Valve
The camshaft actuator solenoid valve adjusts and works with the variable valve timing system in the car. It adjusts the flow of oil to the actuators. These valves can go bad on cars with the V6 and V8 engine. When it goes bad, the check engine light will illuminate on the dashboard, but it can also be accompanied by drivability issues. Regular oil changes are said to help reduce the possibility of them failing.
Passenger Presence Sensor
Yet another sensor that can go kaput is the passenger presence sensor. The purpose of this sensor is to detect whether a passenger is seated in the car. It’s a part of the safety system of the car and ensures that the airbag deploys in the case of an accident. When this sensor fails it will light up the check airbag light.
What to Look For When Shopping For One?
As we have repeatedly said, the 2005 Cadillac STS is loaded with a bunch of advanced (at the time) electronics. Despite being fairly robust, age and lack of maintenance have taken their toll in some cases. Don’t be surprised to run into all kinds of electrical gremlins on cars that haven’t been taken care of.
The known issues listed above have several sensors listed, and they are the most common. However, there can be a couple of other issues that crop up. One has to realize that the 2005 Cadillac STS is more than 15 years old which is why certain problems are a given.
The Cadillac STS was launched from $40,575 for the V6 model. The V8 model, meanwhile, was priced at $47,025 which made the car rather expensive. Nowadays, you can pick up one for less than $7,000. Just make sure you get one without the timing chain issue.
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